夜夜情 = the possibility of becoming exclusive girl friend... % {! C7 W1 `2 D' [0 b0 E
一夜情 = no responsibility...
3 `2 F& d: @/ b" P) B$ }! K7 x2 |' \! g; f' ]! F, f" O' W
I still say only girls who are really upset, or girls who don't value themselves go for 一夜情... smart girls go for 夜夜情, even if it's with many different toyboys.