to aggressively display physical affection towards someone in hopes to hurt them (in a good way) or pop their head off!
physical affection can include nibbling biting, pinching, or squeezing of any body part.
Joaquin: "god dammit, Anna! You're so freaking sexy! Get over here and let me nung
--after the nungging has happened--
Anna: "Joaquin, you can't nung
me so hard. It hurts!"
Joaquin: "sorry, i can't help it. I love you so much i wanna hurt you!"