The Street Thug ghosts were a group of ghost terrorists that attacked the United Nations.
The Ghostbusters managed to trap them when Egon Spengler and Ray Stantz connected five Ghost Traps together while Peter Venkman and Winston Zeddemore stalled them, and activating them when the ghosts chased after Peter and Winston.
When Slimer was put into the Containment Unit to find out what happened to the Ghostbusters, two of the ghosts are seen sitting on a couch-like formation gloating about how Proteus has defeated the Ghostbusters and he will soon free them from the Containment Unit. When they see Slimer spying on them, they start to chase him. The Frankenstein Monster and the Immigrant Family ghosts join the two ghosts. When Slimer escapes the Containment Unit, the ghosts are about to go after him until they see Janine Melnitz pointing a thrower at them, telling them to not even try escaping. They then promptly go back into the Unit.