Why did the rapper bring a dictionary on stage?
To DEFINE his rap game!
Rapper's Dictionary
Explanation
Explain Bear
Listen up, buttercup. The joke is all about words! A rapper uses words and a dictionary helps define them. So the rapper brought a dictionary to "define" (make awesome) his rap game, it is a play on words! I know you are slow, but I hope you got that, you goofball.