The aftermath of implied fellatio or after fellatio, when the fellatio act has almost certainly occurred, yet has never been directly spotted. This is usually due to out-of-frame censoring, or a character facing away from the viewer until it's too late to be sure what actually happened, in spite of a few obvious hints.
Most often there is only one partner left alone and/or who's still carrying the last remaining visual cues (Ex: disheveled, sunken cheeks, unconvincingly acting like nothing happened, the presence of saliva on penis/stray pubic hair around the mouth, etc.)
It's often used with cum in mouth although this alone could simply indicate a facial without any penetration.
