v. int. The act of pushing one's face in between ones scrotum, and rocking one's head side to side very rapidly while making a vigorous, lip-vibrating "brrr" sound.
That chick gave me the best scroterboat ever. My balls are now numb
Whilst manipulating the scrotum with your mouth, shake your head back and forth making a "motorboat" engine sound.
It's the male version of the motorboat.
Last night, Janine was circumnaviagting my scrote and then she went crazy and scroterboated me. I may now marry her.