Spite-eating

Eating something you don't even want, like, or need, in order to deprive someone else.

Could be any food-- dessert, or pizza, or gum.

Also applies to choking down something that is gross, in order to spite someone else, such as to throw a cooking contest.

I really don't even want any cake but I don't want Marge to have it so I'm spite-eating the last slice.

I'm spite-eating this whole bowl of Jenny's nasty chili bc Marge said hers was so much better.