An act of sexual stimulation involving insertion of two fingers in the vagina and the thumb into the anus.

A stupid person; it refers to the lack of surface area on an individual's brain. The general thought is that the more surface area (wrinkles, creases, etc.) a brain has, the smarter the person is. Conversely, a person with a smooth brain (no wrinkles) has less surface area and would therefore be stupid.

It's used for bowling, you pervs!

I'm a bowling ball
And my haters be the pins
Down the lane bro imma spin
Knock yall over once again

2 finger up the females vagina and one thumb up the ass therefore you appear to be holding a bowling ball

A surprise thumb in the butt when doggy style.

Two in the pink, one in the stink.