Towards the end of an athletic competition(usually a basketball game) when one team has obviously secured the win. All of the worst players(scrubs) on both teams who ride the bench finally get to play. Scrub Time usually will not exceed a few minutes in most competitive levels of play and depends upon how big of a lead the winning team has.
Bench Warmer 1: "Hey...it might suck that we're losing by 30 points in the 4th quarter but at least we might get some playing time."
Bench Warmer 2: "Awesome, I love Scrub Time. I was starting to fall asleep a little bit and my legs are numb."