The book by  "Humor in der Mathematik"  by Friedrich Wille (from the 1970s or 1980s) contains the tongue-in-cheek theorem "Up to similarity, there is a unique general triangle".  (Google book search for "Friedrich Wille" "Allgemeines Dreieck")

"General" is defined as "all angles must differ from each other, and from 90 degress, by at least 15 degrees".