Oh Jesus... I just thought of another one. And this one makes me REALLY MAD.
Miniature motorbikes. I don't know if you've seen them, but they're like kiddie versions of Harleys and so on, complete with engines and all ...only ridden by adults.
I'm certain they're not meant to be ridden on public roads, but at least THREE dumb fucks in their 20's-30's ride them around my local streets, getting in the way of cars and generally making a flat out nusiance of themselves. The other day I saw a posse of them standing around a local service station - about 10 or so guys with their weenie bikes, wearing leathers like they're some sort of Munchkin bikie gang.
Don't these people realise they look like fucking tools with their knees around their ears riding a tiny motorbike? Man... and I thought size mattered. :D