I use to think that the phrase "holy shitakie mushrooms" was actually "holy shit, talking mushrooms!"
The latter one still makes more sense.
A childhood belief about swearing

others believed things like this
- I used to think the song"jesus, oh what a wonderful child so holy, meek and mild" was "so holy, Mickey Mouse"— Stephani
- I used to think that mushrooms were meat.Anon
- i used to believe that if i ate mushrooms they would grow on me— gwen
- I used to believe mushrooms were a meat.— Lee Ann
- I used to believe that smurfs were real. I never ate mushrooms. I still don't eat them.Anon
- I used to believe watertowers were giant mushrooms O.o... Don't ask... Really...— Robyn