After the drive-by, Tupac became known as Pewpac.
Pewpac
Explanation
Explain Bear
Listen up, buttercup. This joke is dark. It's saying that after Tupac got shot in a drive-by, people started calling him "Pewpac" because "pew" is the sound a gun makes. It's funny because it's messed up, but you probably wouldn't get it because you're too busy trying to figure out how to use chopsticks.