Too lazy to pick up his pants, Jimmy invents a nanochip which he installs into them so they can put themselves away. However, the nanochip causes the pants to develop a mind of their own and hatch a plot to take over the world.
"When Pants Attack" provides examples of:
- A.I. Is a Crapshoot: Jimmy's nanochip malfunctions, causing his pants to become sentient, take over other pants and attempt to take over the world.
- Animate Inanimate Object: What the nanochip causes Jimmy's pants to do.
- Bittersweet Ending: Jimmy stops the pants invasion and everyone gets their pants back, but he is forced to pick up all the pants in town and it's implied he and his friends will miss the movie they've been planning to see over the past few days.
- Comedic Underwear Exposure: Jimmy, Carl, Sheen, and Cindy all lose their pants as a result of the nanochip affecting their pants. Hugh intentionally invokes this by taking off his pants.
- "Could Have Avoided This!" Plot: Carl lampshades that if Jimmy had just picked up his pants like his parents asked, then the pants invasion wouldn't have happened.
- Dumbass Has a Point: As mentioned above, Carl was right to call Jimmy out on trying to use science to make the pants pick themselves up instead of simply picking up his own pants like a normal, responsible child, which Sheen even lampshades.
- Early-Installment Weirdness: This episode noticeably features pop culture references, particularly Hugh mentioning Luke Skywalker and Carl's Talking with Signs joke being based on Looney Tunes. The series continued to feature pop culture references in later episodes, but the references would be a lot more subtle.
- This is also the only episode (specials included) that featured an illustration along with the episode title. All other episodes just feature the title in a special font with neutrons in the background.
- Goofy Print Underwear: Cindy's polka-dot panties and Sheen's Ultra Lord underwear, which basically have a giant orange spot on the seat. Hugh has the classic white with red hearts boxers.
- Hand-or-Object Underwear: Played with. After losing his pants, Jimmy attempts to hide his underwear with his remote, Cindy uses her diary to cover hers and Carl (despite being too wide to completely hide) uses his hands.
- Shout-Out:
- Hugh mentions Luke Skywalker during his talk with Jimmy at the beginning.
- While she and Hugh watch the pants in their home, Judy states it's just like The Birds.
- Jimmy's final standoff with his pants is similar to The Good, the Bad and the Ugly complete with similar music.
- Carl uses signs to speak during said standoff, similar to characters on Looney Tunes.
- Tempting Fate: After Jimmy loses his pants and attempts to cover himself, Carl, Sheen and (especially) Cindy take the opportunity to laugh at his embarrassing situation. Cue them losing their pants and Jimmy pointing it out, putting them in the same spot.
