I want back the unused salsa at a party
Why do you want the salsa back?
I didn't get to eat it.
You brought it for the party. If you take it back now people will think you are stingy.
It's good to be stingy and protect your belongings.
I think it's nice to leave the food you brought for the host to eat if they choose to do so, even if there are leftovers.