LOL I can't remember much about the film but apparently this is supposed to be a sex shop. I'm looking at what's behind her and its like DIY tools like hammers, wrenches... ;) Maybe its a sex shop for the Village People.
I don't know that you can steal your own joke. Since the Police Squad series lasted less than one full season, I'd say the joke is in play. The Naked Gun bust was more impressive anyway. They stole other jokes, too. Like, "Not that bad!"
There are two meanings of 'bust' that are being played on here. The first is a police raid on a criminal establishment, where they shut it down and arrest the criminals involved. The woman thinks that the police are there to shut down her store, which if I'm remembering right is a porn shop (which tend to have trouble with the law). The second meaning is a woman's chest. Drebin thinks that the woman is referring to her own chest, which is prominently displayed by her outfit, and gives her an awkward compliment about it. The humor comes from the mismatch of interpretations, and the fact that very few people would interpret the woman's statement the way Drebin did.