Ren and Stimpy are adopted by George Liquor to be his pets. Upon arriving home, he introduces them to their new abode: A fish bowl from which the fish was rudely thrown out (and stole George's car as a result). The next day Ren and Stimpy awaken to find George Liquor dressed as a drill sergeant to train them to be proper pets. Their first lesson is how to poop on a newspaper. Ren fails, but Stimpy easily does his business while reading about mudslides in India. He is given a cigar-shaped dog treat as a reward. Next they are taught how to be punished. To learn how to be punished, first they have to learn to disobey. George Liquor tells them NOT to go anywhere near the couch, then instructs them to do just that so they can be punished. When he begins to become enraged by them not following his orders, Ren freaks out and collapses to the floor sobbing, and a terrified Stimpy hurls himself onto the couch as George had instructed, only to be yelled at. Stimpy is scared, thinking he's going to be punished. Instead, George compliments him for following orders and gives him another dog treat. Then George asks Ren to ask him for punishment. But George insists that Ren is too "soft" for punishment and instead gives him 20 dollars and tells him to take the car and see a movie as well. Ren points out that the fish already took the car and it looks like George is going to be enraged. Instead, he gives Ren another 20 dollars for being a smart mouth. Lastly, he teaches them go to protect their master. But before they learn to defend, they have to learn to attack. Wearing a padded suit, he urges the two of them to attack him. Stimpy refuses because George is his "kind and beloved master", but Ren, who is sick of George Liquor and his lunacy, picks up a oar and begins beating him up with it, much to Stimpy's shock and dismay. Again, Ren expects George to be enraged. Instead, he calls him a champion and produces cigar-shaped treats for all of them. The episode ends with the three of them dancing with the cigar-shaped treats clamped between their teeth.
- "Man's Best Friend" was originally going to air in the second season, but the episode was banned by Nickelodeon for excessive violence (Ren beats up George Liquor to near-death with an oar), reference to tobacco, and several scatological jokes. The episode did not see airtime until Ren & Stimpy "Adult Party Cartoon". Spike's official episode lineup on their website seemed to suggest that they consider "Man's Best Friend" a part of the Ren & Stimpy "Adult Party Cartoon" series, but this episode in general is not counted as one of the three episodes from this series that did not air in the U.S.George Liquor is seen again in a later episode, training Ren and Stimpy for a dog show.
- John K. was hoping this would have been another one of his masterpieces of the season, but due to the scene that caused it to be banned, he failed to do so and was fired by Nickelodeon later on.
- Another reason why this episode is banned is because George Liqour says " What's this crap?"
- However, in Wiener Barons Stimpy says "crappy" eight times and Ren says it once.
- Despite John K. lost his job the show still shows crude humor.
- George Liquor is voiced by Michael Pataki in this episode.
- This episode later aired on Spike TV on Ren and Stimpy's Adult Party Cartoon with a TV-MA rating.
- The episode title and scene where George Liquor buys Ren and Stimpy are a tribute to Merrie Melodies cartoon Elmer's Pet Rabbit (1941).