Proboscis Luke started as a a post in r/copypasta and had since been a niche joke within the Star Wars fans.
When I was a kid I had a surreal and terrifying experience watching a VHS of the special edition of Star Wars: A New Hope with my mom. I believe this was the late 90's (1998?) but I can't give an exact date so I apologize, however I was approximately 11 or 12. Basically we were watching the part of the film where they're in the Death Star. At one point when confronted by stormtroopers, Luke's nose suddenly extended grotesquely into a strange flesh-colored elephant's trunk. It then flailed around making elephant trumpet sounds scaring the stormtroopers off. I vividly remember this, and I was absolutely terrified. My mom was really jarred and confused and trying to calm me down. Leia then says "that's enough Proboscis Luke" and his nose returned to normal. The film also continued on as normal. Every subsequent viewing of our VHS was completely normal, as with every previous viewing. We had already watched the film multiple times prior to the incident so that precludes it being some strange edited copy which would be weird in and of itself.