baby butter
The kind of butter that makes a woman fat, in a pregnant sort of way, if it enters through vaginal intercourse. Ironically, this butter can be part of a fat free diet if consumed orally. The latter use is recommended for most women. Also commonly referred to as semen, jizz, love spit, etc.
Her: Rub some cocoa butter on my back, honey!

Him: I'd rather put some baby butter on your face, dear...