I'm not sure I'd have the nerve to use a character from a comic that the forum is discussing, in that forum (iyswim). It also tends to confuse me when people use a character whose gender and/or mannerisms are at odds with their own.
I've variously used Bob from Rex The Runt, a headshot of me in a red Santa hat at Christmas, a South Park version of me in front of a Buck Rogers style cartoon rocketship, and the current socks from a group bicycle ride a few years back (where we were missing a cyclist who had previously worn some very striped stockings). I can't remember why I picked Bob, other than I like him. I'm not a dog with a big gun, or very enthusiastic about sausages, and I'm certainly not a "Big, fat, jelly-wobbly, fat bastard", although arguably I am a bit of a slob.