The Boyfriend Complexity
The Big Bang Theory Season 4 Episode 9 (11/18/10)
Penny asks Leonard to lie to her father and pretender to be her boyfriend. The goofball takes much glee in pretending to date her again and getting to kiss her. Leonard bonds with her father, Wyatt (Keith Carradine, and when Penny reveals it's a sham, Wyatt begs Leonard to do what it takes to get back together with Penny.
Meanwhile, Raj invites Howard to pull an all-nighter with his giant telescope at work. Howard brings Bernadette and wants his best friend to bond with his girlfriend. Raj is stuck getting drunk in order to talk to her and ends up trying to kiss Bernadette, and Howard jumps in to stop and ends up on the other end of the kiss.