In the crossover with the Real Ghostbusters, the original Egon is surprised to learn they live with the Sedgewick Hotel ghost but also they named him.

Although the green ghost with an endless appetite called Slimer has been synonymous with the Ghostbusters for years, it wasn't until their crossover with the Real Ghostbusters that they learned of his name. The ghost famous for sliming Peter Venkman saw a huge surge in popularity thanks to the popular cartoon which lead to him becoming their mascot. While Slimer's popularity has remained constant with fans, the little green spud remains a formidable entity in the IDW Ghostbusters comics. Although it wasn't Peter who discovers the ghost's given name, the reaction is still just as hilarious.

The disgusting blob who enjoyed terrorizing the guests and buffets of the Sedgewick hotel was the Ghostbusters first official case. Although he escaped along with the other ghosts after the Containment Unit originally exploded, the Real Ghostbusters episode "Citizen Ghost" attempted to explain why he remained with the paranormal investigators. After the Ghostbusters rebuilt the Firehouse and continued their business, the ghost continued to appear, showing itself as friendly and non-threatening compared to before. It was Ray who named the ghost Slimer, a tounge-in-cheek jab at Peter who maintained a friendly rivalry with the unorthodox spirit. The IDW Ghostbusters, which followed the films' timeline, maintained Slimer's image of a relentless and vicious entity whose hunger knew no limits. The ghost was constantly escaping captivity to be recaptured and placed into a Paranormal Containment Research Tank where he would be subject to observation and tests.

Although the nickname would occasionally be used by the Ghostbusters, it wasn't made official until the Get Real! crossover by Erik Burnham and Dan Schoening. In the story which deviates from the Real Ghostbusters episode "Janine Melnitz, Ghostbuster", the animated Ghostbusters return to the Firehouse following a battle with the god Proteus. After noticing details in their headquarters are different than they remember, they accidentally release the original Slimer whom they subdue and trap. After both versions of the Ghostbusters meet, the original Ghostbusters use their experience with the multiverse to help their animated counterparts get back home. After comparing notes and helping on the occasional call, the Ghostbusters use their dimensional door to travel to the Real Ghostbusters universe. While at their Firehouse, the original Ray comments on the high PKE readings and unusual odors to which the RGB Egon comments are due to Slimer. He clarifies this is the name given to the spirit from the Sedgewick, much to the surprise of the original Egon.

While the original Ray has his own encounter with the RGB Slimer that he didn't want to talk about, this hilarious crossover between Ghostbusters made a subtle change to the character. Although it appears the original Ghostbusters don't often call it by name, its impossible to ignore that they know in other universes, Slimer has a name and place within their franchise which Peter Venkman must have some thoughts about.

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