I fucked a chick named Macy, but she had dyslexia.
So I ended up doing the YMCA.
Macy Has Dyslexia
Explanation
Explain Bear
Listen up, buttercup. This joke is funny because Macy has dyslexia, see? That means she mixes up letters. So, instead of "YMCA" it sounds like "Macy". It's a play on words, which is way too smart for you, clearly.