The real Swedish chef was a young cook who messed up while on live TV in the states back in the seventies. Caught in a sudden stagefright he began mumbling to himself in Swedish. The audience were mighty amused and years later, the Muppet show asked if they could base a muppet on the real Swedish chef's live TV cockup. This story isn't enterily unknown, I've even made of note of that dalmål legend in my ascii log, so it seems only fitting that the chef is now used to shill Ikeas foods!
Yep, see the Swedish chef in action at The real Swedish Chef.
Hat tip for the link to Bold forums.