In "Pillow Talk" Caitlin says Jen has the cutest booty in the mall.
This exchange from "Role Reversal":
Caitlin: Well, I'm looking forward to it. It's not like I'm asking a boy out because I'm unattractive and desperate.
Jen: Wait a sec, I've asked out plenty of boys! Do you think I'm unattractive and desperate?
Caitlin: You're definitely not unattractive... (Beat) ...or desperate!
In at least one episode, Caitlin called Nikki "hot".
Tricia and Caitlin. Tricia's whole character revolves around Caitlin and how to make her life miserable. The brief time that Caitlin stopped working at the Lemon suddenly Tricia dumped her other friends to get back with Caitlin.
It's very subtle, but there's a moment in "The Journal" when everyone (except for Jude) is reading Jen's diary to the entire mall. During all of these embarrassing reveals, Jen is revealed to have made a bar graph about Caitlin and Nikki's butts. She says that Caitlin's is the "highest" and Nikki's is the "roundest". She would not have known that if she wasn't checking them out...
There's also the fact that Jonesy has hit on cross-dressing Jude more than once, not realizing who it is until he talks. They also have a moment while Jude is helping him make a bowl.
Jonesy tried teaching Jude how to kiss which resulted in Jude taking it the wrong one way and kissing him.
