Wipes Butt With Josh Allen Jersey

AEW star MJF had an all-timer of a promo at Dynamite on Wednesday ... ruthlessly insulting the hell outta Josh Allen and the Bills -- and he did it in front of a ton of Buffalo fans!!

The hilarious moment went down at KeyBank Center ... when MJF made his return to the ring after months away. He started off praising the NFL quarterback and the city, but quickly turned on the audience -- disrespecting their appearance, their quarterback and even their incomes.

MJF called the crowd "grotesque, poor lard asses" as he unleashed the iconic promo ... with fans making sure they were pissed with his words.