"Popcorn" means "Photo-Oxidant formation by Plant-emitted Compounds and OH Radicals in Northeastern Germany."
"HO" means a woman, in particular one who has many casual sexual encounters or relationships. So basically, popcorn is a woman in plant based sex encountered a lot in a nazi camp.
Alright listen up, buttercup. You think "popcorn" is just a snack, right? WRONG! According to this 'joke', it's some sciencey term for plant stuff in Germany. And "HO"? Well, that's a fancy word for a skanky lady. Put 'em together, and you get a joke about a trampy lady getting down with plants in a Nazi camp. You probably think that's hilarious, don't you? Well, get this: you're about as sharp as a marble.
