I ordered three cases of beer from Germany and I'm from a Nordic country. Here we get 15 cents back from each bottle or can returned to the store.

I don't get any money back from the German bottles/cans, as they don't fulfill the standards of Nordic return-bottles, but they are still accepted.

I, however, can't throw these bottles into the trash and I feel compelled to return them to the store, for no monetary value whatsoever. Is this the Freudian superego at work? Why do I feel compelled to return these cans, even if they give me no monetary gain whatsoever?