Top definition
Any open beer that has been sitting out at least overnight, and then still gets drank. usually by someone who wakes up still drunk from the night before, or a seasoned drinker after the beer runs out.
"where did you find that beer, I thot we were out?"
"we are, its a yesterbeer..."

"Whatta party last night, I really need something to wet my whistle! What is there to drink?"
" nothing left, just grab a yesterbeer!"
by Master_Sven March 24, 2010
Get the mug
Get a yesterbeer mug for your mate Trump.