Strong Pen

Alright, listen up, buttercup. This is Explain Bear, and I'm here to break it down for you slowpokes. The joke here is a "pen" can mean two things. First is a writing tool, but you ain't ever heard of a strong writing tool. The second meaning is slang for a penis. It's funny because it makes the reader think about the poster's weiner! Now, wipe that confused look off your face; you look like you're trying to solve a quadratic equation.