When Taichi helps Yui get over her androphobia. They happen to be switched at the time, so he kicks Yui (in his own body) in the groin. They then switch back a matter of seconds later. He was in pain for at least the rest of the night.
When Yui reveals a huge cache of snack food, bought due to having a desire unleashed while she was shopping the club room devolves into one hilarious, desire fueled feeding frenzy.
Inaba's telepathic confession to Taichi at the end of the anime, which has her thoughts say "I love you" again and again and again while her mouth keeps telling Taichi not to listen.
In the first episode of the anime, right after Taichi first finds himself in Iori's body in the empty classroom and, with disbelief, ends up fondling his own/her breasts, right when Fujishima appears at the door with a look of shock on her face. Ready to receive a sound disciplining from the strict and proper class president, Taichi is as surprised/horrified as the audience when Fujishima flashes what could only be described as a "rapist smile" and moves to his/Iori's side saying "It feels a lot better when someone else is fondling them for you." Que a hilarious struggle.