Pack Your Bags
Telling your lover they have to take it up the butt or else they're out of the relationship. It's like the worst ultimatum ever, and it's usually from someone who doesn't even like butt stuff.
He told her she had to do it or leave. She left.
He said he'd break up with her if she didn't take it up the butt. She took it up the butt.
He threatened to leave if she didn't take it up the butt. She took it up the butt and he stayed.