The riddle asks: "What has 4 eyes but can't see?"

Answer: Mississippi

Explanation: Mississippi has four "i" letters in it. That's it. Four "i's" - get it? Eyes! Kind of a clever little trick there. The word itself is just sitting there on the page with those four little "i's" dotted throughout. M-i-ss-i-ss-i-pp-i. Count 'em.

Words can't actually see things. Obviously.

The whole thing works because "eyes" sounds exactly like the letter "i" when you say it out loud. A play on words. Kids love these. It seems these simple wordplay riddles never really go out of style. Brain teasers with puns built in.

Not entirely clear who came up with this one first. Been around forever. Still stumps people sometimes.