This is word play: In English you can say that a nose runs. It means when you have a cold an you need a tissues to wipe your nose. "My nose is running." you can say that someone's feet "smell", which means that person's feet stink. "Your feet smell!" So those are more like idioms. In "real" language your nose smells (you smell the flowers) and your feet run (like running a race.) The figurative language is opposite of the real language.

thanks :)

Example: I have such a bad cold that my nose is running all the time. Don't take your sneakers off young man, your feet smell terrible.

a runny nose is when liquid (snot) comes out of your nose because of a cold, allergy, or crying smelly feet means the person's feet have a bad odor