Jarrell "Big Baby" Miller says Anthony Joshua forced a "bitch ass rematch clause" into their fight contract ... telling TMZ Sports he's already preparing to knock the dude out TWICE!!!
We spoke with "Big Baby" after his clash with Joshua in NYC on Tuesday -- where Miller straight SHOVED Joshua while promoting their June 1 championship fight at Madison Square Garden.
Miller knows he's the underdog in the fight ... but says the critics can "kiss my ass" -- telling us he's 100% confident he'll hand Joshua his first "L" when they throw down.