Stan's Tattoo

Stan's tattoo was in one of Dipper's Guide to the Unexplained. Stan's tattoo is shown on bills face/ body in "Dreamscaperers" when Gideon told him he wanted him to go into Stan's mind and on Stan's machine at the end of "Gideon Rises" Shown in the pictures below.

So Stan's tattoo is that symbol. But what does the symbol mean exactly? I don't know what it means but I found a picture on another site about the kinda squiggle line on the top right.