"It's not our fault he's got a 1 inch d**k" -- Lenny Dykstra on Bagel Boss Guy.
Yeah, the trash-talking has begun between the ex-MLB superstar and his celebrity boxing opponent ... and Lenny's already aiming below the belt.
"On the 28th of September, you're gonna see a f**king ass kicking," Dykstra told us at the Vivid Cabaret in New York City ... "If I don't beat him, I'll be a ballerina dancer."
What's interesting about this clip ... Lenny says he wants a SECOND fight after Bagel Boss -- and he's calling out his longtime enemy, Mickey Rourke.