Dyslexic Who

Hey, listen up, dummy! This joke is all about wordplay. Dyslexia is a condition where people mix up letters when they read or write. So, the punchline is that the person is calling you "You" but they're pretending it's "Dyslexic You", because they are dyslexic. It's funny because dyslexic people mix up letters. I bet you are mixing up your underpants with your hat!