I don't think most of the things mentioned so far are real catchphrases, at least not in the sense I mean. A catchphrase should be something specific to one MC. It doesn't have to be a unique phrase, sometimes it can just be the way it's pronounced. Jammer's "Neckle" is an example of a catchphrase. D Double E's "Uuh-uhh" and "It's me" (the way he pronounces it, like "It's muuye") are other examples.
There are loads of them, but right now I can't come up with any...
In dancehall it has been almost compulsory to have one as an up and coming artist. Like Red Rat's "Ooh noo", Elephant Man's "Corny niggaz" and "They should now" in the beginning of his career, and later "Fo shizzle" and "Yep! Good to go" and Vybez Kartel's "Up to di time"
Many of the Youngers have good ones, like Royal. I don't know what he says, but it sounds cool. It sounds something like "Geniate-ate" Anybody knows what the heck he's saying?