Terence Crawford Beat Everyone's Ass Growing Up, 'I Stayed Getting In Fights'

Back before Terence Crawford became a world champion boxer, he used to whoop people's asses for free on the streets ... telling TMZ Sports, "I used to stay getting in fights."

We love a good origin story ... so when Bud came to the TMZ offices, we asked the undefeated 32-year-old superstar when he KNEW he had a knack for fighting.

"I always knew I could fight," Crawford says ... "I was 4'11" in the 9th grade. I was a little guy ... I think I had that little man complex."

Now, Crawford is 5'8", 147 pounds and arguably the best pound-for-pound boxer alive -- so yeah, he doesn't hand out ass-whoopings for free anymore!

In fact, he's facing undefeated Lithuanian star Egidijus Kavaliauskas (AKA The Mean Machine) on Dec. 14 at Madison Square Garden and says he's ready to show the world why he's the best.

We also spoke with Crawford about Errol Spence -- who was a potential opponent before Errol's bad car crash last month.