look up any word, like dirty sanchez:
 
1.
A word used to describe the emotion felt when seeing an attractive female, often used enthusiastically and repeatedly amongst the male population and at an alarmingly high rate during the consumption of alcohol.
Brent: cheryl cole's on the tv
Trey: biong!

-Several pints later-

Brent: was that cherie blair?
Trey: BIIIOOOONNG!!
by Harv13 July 20, 2010
 
2.
in referance to an ass that prodtrudes so far that it practically biongs when they walk!
omg did you see that ass, BIONG baby!
by Jade is the sweetest October 26, 2005