When you hear someone coming just after you came on yourself after jerking off, and you quickly lick your fingers to clean yourself up so you don't get caught with a sticky mess.
Nub said he had to pull a fingy lick because he heard his mom coming up the stairs on the way to his room yesterday.
when your fucking doggy and stick you finger in her asshole and fish out a piece of shit then plug her noise with it while covering her mouth with your other hand so she has no choice but to breathe in poop through her nose.