When it is time to get into a fist fight.
Synonymous to "throwing down".
Based on the opening scene of Tradewest's 80s hit arcade game "Double Dragon" where Billy and Jimmy Lee step out of the garage, and proceed to start kicking some ass.
Guy #1 "Dude, that guy wont leave your chick alone."
Guy #2 *punches hand and gets up with purpose* "...it's garage time"
Guy #1 "YEAH it is...." *gets up too*