Foul is the husband of Pig Grungy and the father of Bug Grungy and Smelly Grungy. He purchased the Ghostbusters' Firehouse while the team was gone on summer vacation and got rid of their equipment and damaged the Containment Unit. Foul decided to keep one of the Proton Packs to use to clean up after the family pet, Yuck. Foul mistook the entities in the Containment Unit as squatters and tried to chase them off the property.
After everything was sorted out, Pig made him apologize to the Ghostbusters. When Bug did the same and complained about it, Foul encouraged his son saying "That's my boy." Foul agreed to give back the Firehouse to the Ghostbusters on account there was no peace and quiet.
- It is implied that Foul is one of those ghosts that have always been ghosts, as when the Ghostbusters try to warn him of the Containment Unit and he thinks they are trying to trick him, he says "I wasn't born yesterday. In fact, I wasn't born!" 
- Though it is also possible that he meant that he died before he was born and grew up after becoming a ghost.
- Foul is a parody of Homer Simpson.
- The character names are parodies of Married: With Children characters. Foul Grungy being Al Bundy, Pig being Peg, Bug being Bud and Smelly being Kelly.
- On page 11 of Ghostbusters Issue #11, Foul Grungy makes a non-canon cameo on a box to the right of Winston.
- ↑ Pig Grungy (2009). The Real Ghostbusters - "Guess What's Coming to Dinner" (1990) (DVD ts. 02:01-02:04). Time Life Entertainment. Pig says: "Oh, Foul. I love it!"
- ↑ Foul Grungy (2009). The Real Ghostbusters - "Guess What's Coming to Dinner" (1990) (DVD ts. 02:30-02:31). Time Life Entertainment. Foul says: "C'mon, Grungy's! Hustle up!"
- ↑ Foul Grungy (2009). The Real Ghostbusters - "Guess What's Coming to Dinner" (1990) (DVD ts. 15:57-16:00). Time Life Entertainment. Foul says: "In fact, I wasn't born!"