look up any word, like cleveland steamer:
 
1.
A old time greaser.
An over the hill hood.
Hey, check out the old guy, he's a fonzi.
by Robert Michael. Hensel April 17, 2008
 
2.
Sexual act in which the male participant inserts one thumb in the female participant's vagina and the other in her rectum, while saying "Heeeyyeee!" like the character from the popular television show "Happy Days".
Dude, last night I gave Stephanie a Fonzi and she went nuts!
by Bobby Joe Wilson April 20, 2008
 
3.
Sexual act in which the male participant inserts one thumb in the female participant's vagina and the other in her rectum, while saying "Heeeyyeee!"
Dude, last night I gave Stephanie a Fonzi and she went nuts!
by Mister dbagg April 18, 2008