Popular Fungus is a periodical featuring spores, molds, and fungi.
After leaving Delgado's Gym, Egon Spengler was approached by an apparent fan of his. She quickly identified him with a copy of Popular Fungus with Egon on the cover. In a shocking turn, she asked Egon to sign her breasts. It was the result of a computer program Egon wrote that calculated an almost random pattern of words that positively stimulated the brain. Egon planned on publishing a paper on the reactions once he sorted through all the data.
- The title appears to be based on Popular Mechanics.