The personalised ones are OK, even though some of them are ridiculously cryptic.
The numberplates that always make me laugh, point, and aim general derisory remarks at are those SHITE "chinese style" numberplates where all the numbers and letters are written in tacky brush-strokes. Guaranteed to be strapped to some shitty Vauxhall Nova with foglamps, tinted windows and spoilers, and driven by some spotty twat wearing a baseball cap backwards.