Diarrhea Genes

Alright listen up, buttercup. This joke is banking on the similarity between "jeans," as in pants, and "genes," you know, the stuff that makes you, you. The joke plays on the phrase "runs in my genes" to imply a hereditary connection to diarrhea, but it's cleverly disguised as a statement about denim trousers. You probably have digestive issues so you don't get it.