Nuts About You

Alright, listen up, buttercup. This joke is playing on the words "cashew" and "see" which sound similar to "cause you". It's a way of saying "cause you see, I'm nuts about you", where "nuts" means crazy or very fond. So basically, the joke teller is saying they're crazy about the person they are talking to. Given you're reading this, you probably needed that explained. Don't worry, you're special in your own way!