This is the one that made me decide to write this piece. I have to admit, although I hate to do so, I have told this one. In my version, it was a guy I met at a party.
The story is so simple that it is unreal that it has lasted for so long. Basically, a guy takes LSD, then thinks he is an orange, or sometimes orange juice, and that is basically it. In the version I told, he was afraid that we were going to peel him at the party and begged us not to do so. In most stories, he thinks he is an orange for good and winds up hospitalized.
This lie has been around forever, and in the '60s was reported as factual in the news.
I also used to tell a story about a girl at a party who took acid, and ended up thinking she was a duck. She took off all her clothes, got in the tub, splashed around and started quacking. That one was a lie too.