Someone who doesn't know how to spell wagon or comes from the UK.
You: omg, that idiot riding the skateboard down that hill with no helmet is such a freakin' jackwaggon.
Me: you mean jackwagon?
You: no, I'm british.
Me: no you aren't.
You: shut up jackwagon.
a giant dumbass who doesnt kno anything. would quite possibly get everyone killed because of his stupidity
man: bob what are you doing
bob: tryin to shoot that gas can
man: you damn jackwaggon