My brother noticed that a guy at work had 4 little foam South Park characters, about 5" tall each. Naturally, Chris would occassionally sneak into the guy's cubicle and "kill" the Kenny character. He started off with simple hangings and crushing deaths, then graduated on to buying Godzilla pieces to set upon and devour Kenny, or GI Joe soldiers firing rifles at a staked out firing squad Kenny.
Mind you, Chris doesn't know this guy, so this coworker doesn't know who the hell keeps gathering the 3 friends around their deceased buddy.

In the true spirit of brotherly assistance, I made an addition to the prop collection and mailed it off to Chris. He returns the favor with jpeg photographs. He even boned up on his French a little.

By the way, if you know a coworker who's wondering who keeps killing his Kenny, don't forward this URL to him. It might be him.

Napolean Cartman overseas the execution of Kenny via La Guillotine. The "blade" of the device is a standard straight razor blade. The squiggly white line along the far upright is a string that's been frayed to look freshly cut.