The phrase used to describe a person who goes into public and has problems doing regular tasks such as conversations, loading dishes, or anything that requires exertion due to being very, very highly intoxicated on marijuana.
These kinds people are not intentional in there actions and are fun to hang around to laugh at, but will need to be constantly looked over so they don't get arrested or hurt.
You can usually prevent the cops being called on them by explaining to witnesses that your friend has severe autism.
Employee: Welcome to McDonald's, can I take your order?
Flop: hey whats up bro. what's like the very best thing you have here man.
Employee: Well, I like the number 7.....
Flop: oh dude hey do ever wonder whats on the other side of the moon? i bet there are like aliens up there bro. ive seen documentaries about it. it was pretty enlightening.
Employee: Ok, what would you like?
Flop: wait what? oh, I want a bean burrito with extra cheese and extra hot sauce please.
Employee: We don't sell that here sir.
Flop: thanks, you too.. *Pulls forward at next window*
Employee: But you didn't ord... What a flop.