Why do cats run around like crazy after pooping?
Cats running around wildly after defecating is instinctive; cats have a habit of burying their poop to conceal their presence and prevent being discovered by enemies. Running around wildly after defecating could also be because the cat finds it smelly—cats have a much more sensitive sense of smell than humans. Running around wildly might also indicate that the cat is happy and needs to run around to release the stress after relieving itself. 
out of instinct
Cats running away after defecating is instinctive; they bury their feces because their ancestors lived in the wild. Burying their feces helps them conceal their presence, and running away is to avoid being discovered by enemies.Cat poop smells too bad
Cat poop smells terrible. If people find it disgusting, then cats, whose sense of smell is far more sensitive than humans, must find it even worse. Cats will run around frantically to get rid of the lingering smell of poop on their paws.Happy
A cat running wildly after pooping might be because it's happy. After using the litter box, the cat feels refreshed, so it might choose to run wildly to tell its owner about its joy.
