f.f.y.a.
f. f. y. a. is when you shove your fingers up someone's butt so deep it feels like they're going to explode.
I did f. f. y. a. to my sister and she said it was like a volcano.
My dad did f. f. y. a. to my mom and she screamed like a dragon.
At the concert, my friend did f. f. y. a. to his girlfriend and the crowd went wild.