Friendships were a big part of The Big Bang Theory and one of the best things about the show. From Leonard and Sheldon's years-long friendship that alternated between adorable and downright frustrating, to the often odd and funny one between Beverly and Sheldon. While most of these were funny enough to keep viewers watching, few kept the audience coming back for more like Sheldon and Penny's friendship.
The two had a rocky start, due to their completely different characters, but with time, learned to love and appreciate their differences and evolved into one of the best friendships on the show. There are plenty of Penny-Sheldon moments that highlight this and many quotes from the two of them and other characters that show this just as well.
Sheldon Hugging Penny
"Look, Leonard, Sheldon's Hugging Me!"
For their first Christmas as friends, Penny surprised Sheldon with a napkin that Leonard Nimoy had signed while dining at the Cheesecake Factory. Sheldon was overjoyed and felt the only way he could show his appreciation was to hug her.
This was the first physical between him and Penny and given how he was averse to it, it was a pretty big deal that showed how much she and their friendship meant to him. Penny was part of a small group of people he was comfortable with enough to let his guard down.
Sheldon & Penny's Love Experiment
"I Can't A Time You Guys Weren't In My Life."
In "The Intimacy Acceleration," Sheldon and Penny took on an experiment that involved asking each other questions which were said to result in them falling in love. They were completely honest with each other throughout and both itted to caring about each other, with Penny telling him she felt like he and Leonard had always been in her life.
Sheldon's quirks on The Big Bang Theory often frustrated his friends, making them wish he wasn't in their lives. This quote from Penny showed how much she appreciated having him in hers, even though he was sometimes difficult.
Sheldon Feeling Comfortable Around Penny
"It's Easier Around People I'm Comfortable With."
Besides intrusive questions that required honest answers, the love experiment Sheldon and Penny took part in involved another activity where they had to stare into each other's eyes for four minutes. Penny told Sheldon that they could stop because she knew how he wasn't comfortable with prolonged eye and he responded by saying it was fine because he was comfortable with her.
This quote not only shows how well Penny knew Sheldon and the things he liked and was uncomfortable with, but it also highlighted how their friendship had evolved. There weren't many people Sheldon was comfortable interacting with and sharing that Penny was one of them showed how good their friendship was.
Penny Comforting Sheldon
"So, If What You Need Is To Spend Your Birthday In A Bathroom, I'm Happy To Do It With You."
After keeping his birthday a secret from his friends for a while, Sheldon eventually revealed the date to Penny and she and the others convinced him to celebrate it in the season 9 episode, "The Celebration Experimentation." Overwhelmed by the presence of his friends and the call for him to make a speech, Sheldon went and hid in the bathroom and Penny went in and comforted him with these words.
Although Penny had spent less time as Sheldon's friend than Leonard, Howard, and Raj, she understood him better and was much more patient with him. Where the men would have complained about Sheldon's behavior, she was kind and gentle with him and even proposed celebrating in a way that would be more comfortable for him, albeit weird for everyone else. That was one of many times the audience saw how pure their friendship was.
Sheldon's Video Recording
"This Is Penny. She Is Your Friend. If She Offers You Food, It's Safe To Take It."
When an earworm had Sheldon convinced he would forget who he was and everyone around him, he recorded videos talking about his friends and other aspects of his life to remind himself. In one of the clips, he talked about Penny being his friend.
On many occasions, The Big Bang Theory highlighted how picky Sheldon was with food; from the restaurants to having certain foods on specific days. He was even fussy about people touching food on his plate but this quote advising himself to trust food Penny offers him showed how much he trusted, how their friendship transcended all others, and Sheldon's maturity on The Big Bang Theory.
Penny's ions
"Sheldon, You Big Weirdo, I Want You To Know That I Love That You're In My Life."
While Penny was trying to figure out what she's ionate about in "The Closure Alternative," she realized one thing was Leonard and another was her friendship with Sheldon as the two of them had a big impact on Penny's growth on The Big Bang Theory. She immediately went over to tell him how she appreciated him being in her life.
Despite their fights in the earlier seasons, Penny and Sheldon built a beautiful friendship and learned a lot from each other. Several occasions showed this, from Sheldon ing Penny when she quit the Cheesecake Factory to Penny helping Sheldon with his string theory research.
Amy's Feelings Over Their Friendship
"Once In A While, I Get A Little Jealous Of How Close Penny & Sheldon Are."
After Amy and Bernadette were busted by Penny and Sheldon for lying that they were busy to avoid hearing them complain about their careers in "The Anything Can Happen Recurrence," they left to do something on their own. Amy confessed that she was sometimes jealous of their friendship because Sheldon listened to Penny more than anyone else.
Amy was one of the few characters on The Big Bang Theory who was closest to Sheldon and even she acknowledged that her relationship was nothing close to what he and Penny had as friends. Her jealousy was understandable but with time she also grew closer to Sheldon and Penny as well.
Life Lessons Over Breakfast
"We've Decided To Use Our Breakfast Time To Expand Our Respective Knowledge Bases."
Penny and Sheldon started out quizzing each other in the episode, "The Line Substitution," about Kardashians and Venn Diagrams. They explained to Leonard that they decided to exchange knowledge on the topics they knew best.
The whole thing was played for laughs but it showed that they took an interest in each other's interests like good friends would do. It's especially impressive considering how Sheldon often thought of anything else that wasn't academic as unworthy of his time.
Sheldon's Wedding Speech
"I Don't Always Show It But You Are Of Great Importance To Me. Both Of You."
During Leonard and Penny's second wedding in "The Conjugal Conjecture," Sheldon made a short but touching speech about what the couple meant to him. Leonard was his best friend for years, so it was understandable that he felt that way about him. But it was rather touching that he felt the same way about Penny whom he'd met much later and the evolution of their friendship was part of the best storylines of each TBBT season.
Most times, Sheldon's behavior bordered on childish and entitled and he treated his friends poorly, sometimes without meaning to. It was mature of him to recognize this and acknowledge it in his speech to them, especially considering his reaction to them moving in together.
Sheldon's Nobel Prize Speech
"And My 2 Dearest Friends In The World, Penny Hofstadter & Dr. Leonard Hofstadter."
Another example of Sheldon acknowledging the importance of his friendships with Penny and Leonard was during his Nobel Prize speech in the series finale where he called the two of them his dearest friends.
Although Sheldon was friends with the whole group, it was clear he treasured Leonard and Penny more than the others. Out of all of them, those two spent more time with him and put up with his difficult behavior. Penny, more than Leonard, was especially understanding and often intervened when the two men were in disagreement.