My coworker is obsessed with doing favors. Gratitude is his favorite. He collects it and stores it in the filing cabinet under his desk. Recently he did me a favor by recommending me for an open position I did not want—a lateral move into a different (worse) department—which was SUPER awkward to turn down. He did the cleaning lady a favor by telling her he'd get her a leaf blower to make her job easier (he does not have the authority to do this; there will be no leaf blower). And he's doing HR a favor by soliciting complaints about the cleaning lady so that they can fire her after the month is up (first complaint: there are leaves EVERYWHERE!).
On behalf of the entire office, I would like to thank him for everything he does for us.