Of course the perfect gift for the kids of people you don’t like: Toy trumpets and drum sets.
If you don’t like the kids or the parents: A trampoline
Do you remember "Tickle Me Elmo"? I gave that doll to my youngest niece. She adored it. The next day they started their three day drive to get back home. That night my brother called me to complain about my gift.
I told him that he should have been nicer to me when we were kids.
Even though Elmo broke the following day, (how DID he manage to get under the car wheels?) she still loves it to this day and it has a place of honor in her dorm room.