Being taken advantage of in a variety of situations. As if you're bending over, you're in a kind of vulnerable situation where people can easily shove stuff up your ass, and you're taking it with a faint smile.
If he rents this shitty apartment for as much money as their asking, he will totally be taking it up the ass.
A more badass way of saying "I'm sick and tired of repeating myself, get it through your fucking head". May also have implications of "are you calling me a liar?". From the Bruce Willis and Damon Wayans movie "The Last Boy Scout".
I'm gonna say this again, for the cheap seats. (yelling) I DON'T KNOW WHERE JOE HALLENBECK IS! That's my fucking statement! Write it down and shove it up your ass!