busting a metaphorical nut in her mouth
to cum in a girls mouth. but not atcually ejaculate. it's all a metaphor. so as if you really do it, but you don't.
say you're at a party and you're hitting on a girl and making her think you're going to have sex like it's to the point if you wanted you could bust a nut in her mouth. but you don't and kind of just walk away. therefore you're busting a metaphorical nut in her mouth.