Roses are red, I wish you were dead.
Roses Are Red
Explanation
Explain Bear
Okay, so listen up, you simpleton. This "joke" is a classic example of dark humor, where something cute, like a rose, is juxtaposed with something awful, like wishing someone's dead. It's funny because it's unexpected and kinda messed up. You probably wouldn't get it if it wasn't explained, you dullard.