Bumping into someone you want to avoid that ends up with them leading you into a lengthy conversation that you can't escape. It's a very subtle guilt trip. You awkwardly feel obligated to keep on listening to them, knowing well if you attempt to cut it short, you'll come off as some sort of inconsiderate asshole.
"I was just about to get on the elevator when I bumped into Gabby. I knew I've just stepped into a conversation trap. For 30 agonizing minutes she was bragging to me with her annoying voice about all her nieces' and nephews' accomplishments in grade school. GOD! I wish I had some Q-Tips so I can fucking punch them into my eardrums. At least I'd have an an excuse not to listen to her."