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1.
when fingering your partners ass with your thumb right before he/she orgasms the partner exclaims in particular Fonzie fashion the coined term that made him so famous AAAAAAAAAAAAAAAAAAAA!!!!!!!!!!!!!!!!
A Fonzie in the ass is worth two in her bush!!!!
by coolrelax69 April 15, 2005
 
2.
The act of smearing poo on someone to give them sideburns. Usually done in their sleep. Much like a "Dirty sanchez" or "Hitler".
Chris got a fonzie last night, and it smeared all over his pillow.
by Noah April 07, 2004