The sixteenth episode of the first season of Dennis the Menace (1986).
It's a Ruff Life
PeeBee invents a brain wave machine. When he tests it on Joey, Ruff gets into the other booth, causing them to switch bodies. Dennis has to get Joey and Ruff back to their normal bodies, which won't be easy when Ruff-in-Joey's-body causes trouble for Mr. Wilson.
Professor Myron Mentalapse
On a field trip to the science museum, Dennis, Joey, Margaret and PeeBee meet a looney professor named Myron Mentalapse, who uses his time machine to take them back to the Prehistoric era. While there, the time machine gets stuck in quicksand, and Dennis and his friends have to figure out how to get it out while evading a T-rex.
Dennis Race 2000
Dennis and Joey challenge Margaret and Gina to a soapbox race around the neighborhood.
"It's a Ruff Life" provides examples of:
- Eating Pet Food: When Ruff-in-Joey's-body hides in Ruff's doghouse, Dennis tries to get him out by giving him a dog biscuit. Since Ruff now has Joey's taste buds, he finds it tastes terrible.
- "Freaky Friday" Flip: When PeeBee tests the brain wave machine on Joey, Ruff gets into the other booth, causing the two to switch bodies. At the end of the episode, after Joey and Ruff are back in their normal bodies, Mr. Wilson and a bulldog get into the machine's booths as another dog turns the machine on, causing them to switch bodies.
- Here We Go Again!: This episode ends with Mr. Wilson and a bulldog switching bodies with each other when they get into the booths of the brain wave machine and another dog turns the machine on.
- Hidden Depths: After a brief chase from Mr. Wilson and a pack of dogs, PeeBee tells Dennis that he'll explain what happened to Mr. Wilson. Dennis tells PeeBee that he doesn't know Mr. Wilson like he does, and Joey-in-Ruff's-body then says, "Yes, he can be quite obstinate at times." Upon hearing this, Dennis says that he didn't know Joey knew words like those.
- Kids Hate Vegetables: When Dennis and PeeBee explain to Joey what "concentration" means, Dennis compares it to eating vegetables. Joey says "Yuck!" upon hearing this.
- Malaproper: Joey mispronounces "concentration" as "condensation".
- Say My Name: This episode ends with Mr. Wilson-in-a-bulldog's-body saying "Dennis!".
"Professor Myron Mentalapse" provides examples of:
- Alliterative Name: Myron Mentalapse.
- Bamboo Technology: Dennis and his friends build a pulley out of vines and branches to pull Professor Mentalapse's time machine out of the quicksand.
- Canon Foreigner: Professor Mentalapse is not a pre-existing character from the comics and was created for this episode.
- Hates Baths: Discussed; When Dennis and his friends return to their present time, Dennis tells Professor Mentalapse to get his time machine to a car wash. Professor Mentalapse refuses, saying the dirt and muck is precious scientific evidence. Dennis then says he's going to remember that next time Alice bugs him into taking a bath.
- Mama Bear: Dennis and his friends get chased by a T-rex, whom they soon discover is the mother of the baby T-rex they befriended, and is very protective of him.
- Quicksand Sucks: When Professor Mentalapse arrives in the Prehistoric era, he gets his time machine stuck in a patch of quicksand.
- Say My Name: This episode ends with Margaret saying "Dennis!" when Dennis shows her a picture he took of her running from the mother T-rex.
- Time Travel Episode: Professor Mentalapse invents a time machine, and when PeeBee helps him with the time-space continuum formula, he gets it to work. He then takes Dennis, Joey, Margaret, and PeeBee back to the prehistoric era.
"Dennis Race 2000" provides examples of:
- Bamboo Technology: Dennis and Joey build their own go-kart using the junk in Henry's garage, Mr. Wilson's trash can, and Ruff's dog bowl.
- The Big Race: Dennis and Joey face off against Margaret and Gina in a soapbox race in this episode.
- Fruit Cart: Dennis, Joey, Margaret, and Gina drive their go-karts through a market, knocking over several fruit stands. Margaret and Gina both end up wearing fruit hats as a result.
- Girls vs. Boys Plot: When Dennis tells Margaret that boys are better drivers than girls, Margaret challenges Dennis to a race, and upon seeing a box of soap, he decides they should race soapbox racers. Dennis and Joey face off against Margaret and Gina. Thanks to Ruff taking back his dog dish, which Dennis and Joey used as a steering wheel for their go-kart, Margaret and Gina win the race.
- Literal-Minded: Margaret and Gina build their go-kart out of actual soap boxes.
- Removable Steering Wheel: Dennis and Joey use Ruff's dog bowl as a steering wheel for their go-kart just as Ruff is about to have his lunch. When Ruff catches up to them, he takes it back, causing them to lose the race.
- Shout-Out: This episode's title is a reference to the 1975 film, Death Race 2000.
- Watch Where You're Going!: This episode begins with Dennis and Margaret crashing their bicycles into each other. Afterwards, they argue over who is to blame for the accident.
