Tell someone that you're gonna say “I 1 poopoo” and it will go in order of numbers, so they say, “I 2 poopoo” & so on:
You) I 1 poopoo
(Them) I 2 poopoo
(You) I 3 poopoo
(Them) I 4 poopoo
(You) I 5 poopoo
(Them) I 6 poopoo
(You) I 7 poopoo
(Them) I 8 poopoo
And be like, “You ate poopoo??! EWW!!”
Alright, listen up, buttercup. The joke is that you trick someone into saying "poopoo" after "I" and a number. Then you act all surprised and grossed out, like they actually eat poop. It's funny because they didn't mean to say they eat poopoo, but you made them do it! And you, my friend, are probably the type of person to fall for this because your brain operates at the speed of dial-up internet.
Pokémon trainer
What the heck is that ha ha ha ha ha ha ha ha ha ha ha ha ha