Sí, Deez Nuts

Okay, listen up, you chucklehead. The joke plays on the Spanish word "Sí," which sounds like "see." So, when someone says "Si... See Deez Nuts!", it's a play on words similar to saying "Yes, you look good, see these nuts!". You probably still don't get it, but that's okay. You wouldn't know humor if it slapped you across the face with a fish.