Nut cream is a complicated sexual act which probably will become popular in porn movies very soon.
1. You (the man) fucks a girl in the ass and cum on her
asshole (note: not in her
asshole).
2. When the sperm lies there on her ass you take a hold off your balls (hence the term "nut") and puts 'em down her
asshole, then begin to "ballfuck" her.
3. Take out your balls, now dripping of sperm and "brown sauce" and let the girl take a lick (or suck).
This is what you call "nut cream".