When a man puts his foreskin on a woman’s nose and subsequently pulls his penis back, creating a vacuum. When the foreskin slides of the woman's nose, a popping sound is created. Based on Disney’s Dumbo, where the jailed mother elephant hugs Dumbo using her trunk.
Whereas my former gf enjoyed a cozy dickslap now and then, my new one is deeply into trunking.
Dude, that hipster chick you hooked me up with made me trunk her before she would go to sleep.