It tells from the singer's viewpoint about his greedy sister being lucky enough to marry a yuppie, then got divorced and took the yuppie for all he was worth in the proceedings and is now a swinger dating another singer while her ex-husband cannot get anyone interested in him, is possibly bankrupt and is considering suicide ("head in the oven"). In both verses, the singing brother of the sister cannot decide which is worse but is sure what happened to his ex brother in law will not ever happen to him because the singer has "you to save me" and that in "a world gone mad", "yer so bad".
In the music video for "Yer So Bad", the sister and yuppie (played by Charles Rocket) are at their wedding reception with Petty as the photographer, then dissolves to two Los Angeles County (?) sheriffdeputies hauling the resisting husband out of their marital house while he tries unsuccessfully to take as many possessions that he can to his car that he drives off in and dissolves to a National Enquirer-type newspaper with a front-page article about it in bold print block letters called "CHEATING HUSBAND'S HEAD EXPLODES", then later dissolves to a bar where the wife, apparently a singer herself, is laughing and flirting with the band's drummer, who later goes home with her to the former yuppie couple's luxurious spacious house. The expelled husband, after driving down the Los Angeles (?) freeway, checks into a cheap motel across town where he opens a metal briefcase revealing a blow up doll that he is inflating as his new artificial "companion". A construction scene appears with a new house being built and a construction worker wearing a T-shirt that says "DIE YUPPIE SCUM" while sumo-like men are shown dancing on the house's construction site playing cymbals. The video later dissolves to the ex-husband driving in his convertible with his blow-up doll next to him in the front seat, trying to keep it seated in heavy traffic, and ends by showing him walking down the street carrying the doll in public.