A person who is ignorant and generally has no idea about anything.
Don't talk to me like ya know me, ya muppet
Someone who is useless until you shove your fist up them - Just like Kermit !
A nicer way to say you are an idiot, or a retard.
E.G. "OMG you are such a muppet!" or "Haha you muppet!"
You could use this when talking to friends if you don't want to use something as harsh as idiot.
"Well, it's not quite a mop, it's not quite a puppet, but man... " - Homer Simpson
That explains it all
Someone who is usually an idiot and doesn't know much about anything // stupid
an affectionate term for someone who's a bit stupid