implied after fellatio
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.