The worst gift I ever received was a gag birthday gift, I have a friend who thinks they are the best ever. I received a clown lamp. Clowns are scary to me and this one was particularly bad. He had one shoe with toes exposed and painted toenails. In one hand he was holding wilted flowers. I could only imagine some pedophile clown. If the gift wasn't bad enough, that night when I went to bed (after a birthday celebration with a few drinks) the clown was sitting on my bedside table staring at me.
My ex-in laws had a regifting exchange for Christmas celebration so the clown was regifted the next year (after sitting in my garage for a few months... in a trash bag so I didn't have to see it).