Any old McDonald's will do, boxing star Danny Garcia tells TMZ Sports -- 'cause ladies tryna quench their thirst ain't only at the club.

"You just walk down the street -- McDonald's ... buyin' a McGriddle! You can find 'em anywhere!!"

Danny's a 1-woman man ... but we're pretty sure not all his bros have coitus on deck after every fight. Garcia says NFL and NBA guys get waaay more groupie love.

So ... we got D.G. to drop some knowledge on where to look.

Dude's GF is smokin' hot -- so maybe he's right. Maybe.