I think the weirdest combo I've ever had was the red pepper paste on the peppers. (Korean style). The damn things look like they're spicy as shit, but isn't at all. In fact it's sort of sweet, salty and bitter.
But that's not something I put on all my food.
I'm surprised at the turnout for ketchup and stuff like "HP/A1" sauce on meat.
* fohfoh loves HP sauce on steaks