In regards to Levi's commercials, I think that it's simply because the marketers want you to think that if you buy their jeans, you'll find no end of opportunity to take your pants off--and while their EXAMPLES may only be something like dancing-around-in-your-underwear innocent, they hope that the IDEA of taking your pants off will stick around more than the exact circumstances they show on TV. (But then, I tend to think that everything ultimately comes down to SOMETHING to do with sex, and that goes double for marketing.)