Something you say when you are intentionally lying to someone, and they don't realize that you are joking. For instance, if you are making up a story about something that person did while drunk or high, if they legitimately believe you and you want them to know that you are kidding, you can say Eat my poop
Me: "Hey man, remember that time you were so blazed that we got you to drink your own piss"
Sejat: "Oh yeah, I think I sort of remember that"
Me: "Eat my poop"
Sejat "Oh fuck you"