Tree fiddy comes from South Park, first heard in the 1999 episode The Succubus, where Chef's father repeatedly tells stories about the Loch Ness Monster approaching him in disguise and asking for three dollars and fifty cents. Chef's mother and father return with the same joke in later episodes, turning the amount into a running gag. Clips and quotes spread through forums, image macros and soundboards in the 2000s, and the phrase became shorthand online for spotting a disguised monster, a scammer, or any story that was leading to a ridiculous request for money.