When someone gives you a Kombucha mushroom - the "secret to immortality"... nasty things.

or 'friendship bread'.

...these scourges of communication live onnin electronic forn.

...hell. I’d erased that hideous memory. Thanks a lot..

Modern day equivalent is those “copy this post to your status so I know you are paying attention to me” posts.
Coerced participation.

Worst thing EVER.

Worse yet was being invited for dinner and getting there finding out it was a way for friends to get you over to sign you up in a multilevel marketing scheme (Amway, Shaklee, etc.) I detested that and it immediately ended a number of relationships!