I don't particularly do it, but this can sometimes be hilarious. And Offensive.
There's people who do it for laughs, or because they're pillocks. Anyway, here's some.
'Useless' the Patrat
'Silly Dawg' the Lillipup
'Abortion' the Munna
They're a few. I realise that they're a little crap, but y'know. You got any else?