Here’s a list from the creator. I’m not sure if they’re all always there:
“Here is the semi-official list of symbols, more or less in order of frequency of use: eyeball, piece of pie, alien, dynamite, K2, upside-down bird, bunny head, crown, single shoe, arrow in the back.
They began in 1996 when I decided out of boredom to draw a little bird sitting on a shelf where it didn’t really belong”