SonicxReiHino:
You see almost everyone said Cherry's face xD and Shinobu also, I mean he left her for Lum. Doesn't that give reason to why he'd dislike it the most? lol
foxhead556:
I would say Ran's bazooka since explosives always hurt, getting your head jammed into a bench by Shinobou since she has she hulk's strength and Ryunosuke's fist since she is apparently super human too.
cata:
I picked Shinobu (unhuman strenght), Cherry (unhuman appearance and -BOOM-) and Azuka because fear can do real damaging stuff. xD
FallinG_StaR:
I guess the biggest pain is probably just Cherry face/appearence and getting hit by a school desk and/or other furniture.
I don't think that a perv like him will be bothered by getting punched or slaped by a beautiful girl... I think he might even like it... :P