PK was a reference to an old clan I was in. The clan was old in 2000, so I decided to drop PK altogether in 2005. I also went by 'Jamaican Gecko' and 'Fallen Angel' during the time we could change our names, since those were usernames I went by at other forums.
I think my favourite sigs were when LP was banning all the funny people left right and centre so I knocked up a couple of Kill Bill parody posters called Kill TPM, one for each volume, as LP was literally killing TPM by banning all the funny people.