When something's REALLY important. The tags "bold," "underline," and "italicize" begin with the letters BUI, hence the term. When someone using BBCode BUIs something, you know shit's about to go down.
by MegamanTTEX November 03, 2010

The amount of money required to buy a spot in a poker tournament. It's also generally your starting amount of money in the tournament.
by PsyMar June 26, 2004

by Wolfpack69 March 05, 2009

by Joe Ernster esq. August 06, 2007

"buy" is the dance you do while you download music off the internet.(usually in an illegal fashion.)
by Michigan Man March 11, 2009

Dude, it's payday! Come on down to the bar, it's buy-in!
I'll be there....What's buy-in?
You're buying the first round. See you there.
I'll be there....What's buy-in?
You're buying the first round. See you there.
by KillAllHumans September 16, 2004
