Peter smiles at Liz's compliment. Liz was his favorite dance partner, too. He just feels so comfortable around her, even when he might not feel all that comfortable himself.

Like when he's out of his element. Like right now.

"If you wanted me to, I'd do the same thing!" he replies. "Friendship's all about give and take, you know?!"

Peter takes a sip of his soda. There's no alcohol in it, just plain soda and ice.

"I think he probably wants us to have fun!" Peter looks out at Alec.
"But I have fun just doing science homework!"

That's probably where Alec and he differ with regards to "fun".