look up any word, like slope:
 
2.
Noun. A small unit in a group of friends who brings life to the scene, and make's it happening.
The fun-unit always bring the house down!
by KGC January 02, 2007
 
1.
A measurement of fun.
Today's episode of happy days was great it was 50 fun units.
by Dick Assman September 28, 2009