23. RVD 4:20
A takeoff of the famous Austin 3:16 shirt, Rob Van Dam started his own movement with RVD 4:20. You see, RVD 4:20 doesn't mean "I just kicked your ass", it means "I just smoked your ass." With yet another not-so-subtle nod at smoking a certain type of plant, RVD put his hobby right out there for wrestling fans to promote. Many ECW fans were more than happy to put on this shirt and proclaim their love for RVD and his herb 0f choice.
22. Edge and Christian Pose-itively Awesome
Edge and Christian weren't always world champion contenders. As a matter of fact, in 2000 they were more famous for playing clueless beach bum characters in opening matches. That's not to say they weren't extremely popular though because crowds loved the duo even though they were heels. Edge and Christian became known for their Five Second Poses (for the benefit of those with flash photography) and this shirt reflected their fun-loving, if not dorky, attitude.
21. Ox Baker's Shirts
It's really not fair to only include one of Ox Baxer's t-shirts because he had so many made for all his situations. Baker was a true heel who loved to get heat and was not above using his wardrobe to accomplish that. His attire proclaimed that Ox was #1 and that he was the Great Heart Puncher. Ox Baker is an underrated legend who had way too many cool t-shirts to count.
20. Randy Orton's Legend Killer Checklist
Early in Randy Orton's singles push, he took the character of a "Legend Killer" who took out legends of wrestling's past to gain heat. It was a fairly effective character and Orton used it as a stepping stone to the main event level. The shirt was pretty cool too, as it featured a checklist of all of the legends that Orton "killed" along with the dates of their demise.