pacman putting his gloves to the sky before fights mayweather throwing his gloves over opposite shoulder during his name intro
First one that came to mind was Taylor. I think it was his forehead he always touched, though. JuanMa Lopez adjusts his trunks almost after every exchange. Cotto starts every fight bouncing near the ropes, with his back to his opponent prior to the opening bell. Devon Alexander, Antwone Smith, and Anthony Peterson all comically yelp when throwing punches.
roy jones messing with his shorts. mike tyson had the thing he used to do with his neck. tyson fury has that quirky habit of punching himself in the face.
I think my favourite was Hamed's signature flip over the ropes whenever he entered the ring. It was like his personal good luck charm as well as being a statement of extreme confidence. (Apparently the only time he didn't do it was the Barrera fight.)
these guys are still amateur fighters with no pop in their punch they say 'HA!' n **** like that with every shot to get noticed, score points and get attention from judges
jermain Taylor swatting the imaginary bug on his forehead every 5 seconds is probably the most annoying habit ever.