You'll have to explain that one. That's one British slang I haven't yet heard.

'plonker' must be a term unique to England/Scotland.

def: dope, idiot, moron, wally, pillock, dunderhead, dimwit eg: You are such a plonker, Rodney.

I take it you've never seen Only Fools & Horses?

haven't. is it good, cause I might have to rent it then?

I will go and find you a youtube clip. Watch this space!

First time I saw the name I misread it and googled plunk! No wonder I didn't find it.