Just get the keys is the third episode in Cartoons of a Wimpy Kid.
Greg's Dad gets a new security system, which locks both the inside and outside of the house. When Mom and Dad have to go to Rodrick's concert, they leave Greg and Manny in charge of the house. Manny accidently fools around with the security system and locks both him and Greg in the house. When Rowley comes over he tells Greg that the "security system" was actually a piece of gum jamming the door's lock. After that Greg faints.