(this does not apply to all girls)
Drunk sex IMO is always the most fun sex I get. Girls, or gfs are a bit more looser and open minded when they're a little bit liquored; and a little more open minded = a little more adventurous/ push the boundaries a little.
Other than that, when you get into a long term relationship; sex does get pretty routine so this is my favourite way to mix it up with the wife. (it's always a good start and its somewhat unpredictable how it's going to end).
Oh!!!! another thing. (at least with my wife and previous exgfs). Drunk wife/gf + good music =
