A recent discussion on a blog here brought an interesting question to my mind - what is vanilla sex?
Penis-in-vagina missionary with lights out between husband and wife surely is vanilla. Pegging or spanking (not just an occasional slap) probably is not. Enemas definitely aren't.
Is anal sex vanilla? How about oral?
(I realize this may also depend on the locale and time period. Until a few decades ago, anal and oral sex were officially considered deviant and harmful and illegal in a large part of the US. So answers may need to say where one speaks from.)