Revealing mistake: When Joe is being thrown during the fight scene, you can see it's not David Spade, but the stunt guy. (00:27:50)
Revealing mistake: When Joe is strapped to the atom bomb he orders a girl to show him her boobies. When she takes her top off, you see a back shot of her (so you can't see her boobs) but her body is transparent and you can see Joe's arm through her body. Obviously, the girl was superimposed onto the shot. (00:34:40)
Revealing mistake: When Joe Dirt gets lifted up by another man and thrown to the ground you can see that Joe is a stunt double.
Revealing mistake: When the cop drops off Brandy's dad and it first shows him with no leg, you can see his real leg behind him.
Revealing mistake: After Joe blows up the A-Bomb, the film is reversed for a second as is evident by Joe's "I Choked Linda Lovelace" shirt.
Revealing mistake: In the scene where Joe talks to the mean parking guy and then speeds away spinning his tyres, If you look at the pavement there is already a mark where the car had burned the tyres. The shot had been tried once before, leaving almost identical marks from his tyres.
Revealing mistake: When Joe is on the bridge and about to jump, the cop ropes him with a bungee cord. It's a single-stranded cord with a loop like a lasso. When Joe falls, however, it is a multi-stranded bungee cord with a proper ankle wrap. Obviously, it wouldn't be safe if the stunt man jumped with just a lasso, but it's obvious that it's two totally different ropes.
Answer: It's not so much a joke with a punchline, but more like a funny phrase. He was affiliated with the mob, and as such, has most likely been in violent situations. He asks "does your mother sew" and then punches his refelection in the fire extinguisher case (someone's face if a fight was really happening). The "get her to sew that" comment implies that the person he hit would have needed stitches. (thus the reference to sewing.)
Jazetopher
He was referring to fixing the hole left in the clothes after being shot.