Ghost rules are certain physical boundaries/laws placed upon interactions between humans and ghosts, as well as ghostly abilities, in the Dude, That's My Ghost! universe. Several such rules include:
- If a human is not in contact with a personal belonging of the ghost's, they won't be able to see or interact with the ghost. Ghosts can see other ghosts, regardless.
- Despite this being the most important ghost rule, even referenced in the intro, Bobby manages to circumvent this and allow those not equipped with his stuff to see him. Therefore, a ghost can make themselves fully visible if they learn this skill. Another way a ghost can achieve this is by covering themselves with bird poop (i.e: seagull).
- Ghosts can have a physical effect on the living world: if they lift something up, the object will appear to float in mid-air to those not in contact with the ghost's personal belongings.
- Ghosts have to actively choose whether or not they will phase through objects. In Copycat Cobra, Billy says it's an advanced ghost skill to phase through things. However, in Billy Billy Billy Billy Billy, he accidentally allows CDs to phase through him, and in Let's Do Lunch he accidentally phases through pool water he wanted to splash in.
- Ghosts can use their ectoplasm to do almost anything, including self-combust or change shape. In addition, if a ghost's ectoplasm gets on an inanimate object, it can give the object unusual, ghostly properties until the ectoplasm is removed.
- A ghost ability must be learned: no ghost can make anything with their ectoplasm until they know exactly how to do it.
Billy Joe Cobra
- See also: Billy Joe Cobra/Abilities
Billy Joe Cobra is one of the deuteragonists of the show. Before becoming a ghost, he was an uber-famous rock star. He is actually pretty bad at being a ghost.
Spencer Wright, Rajeev, and Shanilla can only see Billy Joe because they wear one of his personal belongings at all times. Spencer wears a bright blue guitar pick pendant shaped like Billy's head, Rajeev wears a red belt buckle that has Billy's face/logo etched onto it, and Shanilla wears a small pink bracelet or watch without any distinguishing qualities.
If the three weren't wearing their Billy Joe Cobra accessories, Billy would be as invisible to them as he is to everyone else.
There are examples of ghost rules applying to Billy outside of the central trio, as well.
In Billy Joe Cobra Museum, Sam Hoover is shown to be wearing a pair of white underpants sporting Billy's face (opting to wear it as a one-piece over his clothes instead of wearing it as actual underpants), and thus is also able to see him. Principal Ponzi also sports a pair of BJC undies during the events of Billy Joe's Last Fan.
In School Of Terror, Spencer tricks Mr. Minotaur into wearing a fedora of Billy's (also with Billy's face printed on it, as well as a singular feather in the back), making him capable of seeing Billy pretending to be Lamuel P. Gompers.
In The Candidate, after all the students have been sentenced to the Loser Train by Lolo Calorie, Billy places a sombrero of his on Lolo's head - also with his face on it - and pops his head up through her soup to speak with her in his "Mexican" form. Lolo is scared off instead of befriended, but she does see Billy while she has the hat on.
In True Party, the reason why Billy's autopilot recognizes him, even as a ghost, is that it wears a tiny little BJC hat.
In How To Impress Ladies, Billy puts spiked bracelets on his fan girls to let them see him, due to the fact they were about to become Spencer's fan girls instead.
- See also: Bobby: Abilities.
Bobby is a one-time character in Copycat Cobra. He has way more ghostly abilities than Billy does, despite being no less ghostly than Billy is, due to his ability to learn unbelievably quickly.
At first, only people wearing his retainer could see him, just as someone has to wear Billy's gear in order to see him. Then, he learned how to let himself be seen by people without any of his gear. It is unknown where exactly he learned such an ability from.
During the course of the episode, The Ghost of Spencer Wright, Spencer Wright becomes a ghost when he accidentally consumes some of Billy's ectoplasm. He appears to have all beginner's ghost abilities, same as any other ghost, and abides by Ghost Rules 101. However, he is able to become human again when he pukes up Billy's ectoplasm to get it out of his system.