Rules governing costumes became established in response to specific costumes and costuming trends . The first nude contestant at a Worldcon masquerade was in 1952 ; but the height of this trend was in the 1970s and early 1980s , with a few every year . This eventually led to " No Costume is No Costume " rule , which banned full nudity , although partial nudity was still allowed as long as it was a legitimate representation of the character . Mike Resnick describes the best of the nude costumes as Kris Lundi wearing a harpy costume to the 32nd Worldcon ( 1974 ) ( she received an honorable mention in the competition ) . Another costume that instigated a rule change was an attendee at the 20th Worldcon ( 1962 ) whose blaster prop fired a jet of real flame ; which led to fire being banned . At the 30th WorldCon ( 1972 ) , artist Scott Shaw wore a costume composed largely of peanut butter to represent his own underground comix character called " The Turd " . The peanut butter rubbed off , doing damage to soft furnishings and other peoples ' costumes , and then began to go rancid under the heat of the lighting . Food , odious , and messy substances were banned as costume elements after that event
30th WorldCon
30th World Science Fiction Convention
Cosplay