I have gotten some head-scratchers but nothing especially notable.
The following was the worst gift I witnessed -
The sister of the guy I was dating was absolutely desperate to get engaged. She was in her mid 20s and had dated the guy for a couple of years. When I say she was desperate, she was absolutely consumed with sealing the deal with this guy. In her mind, marriage, house, kids, etc. needed to happen asap if not yesterday.
One of her uncles thought it would be funny to wrap up a fake engagement ring for her to unwrap during the family gift exchange. It say it wasn't funny is an understatement. The boyfriend was furious and went bonkers (and seemed truly disturbed by the impact the "joke" had on his gf) and the sister (gf) was upset and humiliated. His prank ruined the evening. It was an odd family and some of the members definitely had an "odd" sense of humor.
Year later I heard they did eventually get married (and later divorced).