The act of putting your schmungus, inside a female of your species, and violently spinning your body around whilst inside to cause internal damage, or decrease their morale.
My girlfriend was cheating on me, so I hid the fact I had known, and begun the Schmunging
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.