How do I get him to stop talking all the time? He never leaves me alone, and I've tried everything I can think of, rude or not, to make him stop. Most of the time I'm trying to do other things, and it's distracting to have him going on and on. Especially since I have to pretend to listen. Most of the time his topic is of no interest to me, but he holds it against me if I say so, and says it's rude not to listen.

What am I supposed to do?