"What do you do?"
Seems to be a default, go-to dull question asked by just about every single random stranger I meet or am introduced to (other than fellow students). It's essentially a one-way deathtrap to a situation where I have to listen to someone drone on about their job and pretend to care.
And it's so hard to get out of. Sometimes pretending to interpret it as a question about 'things I like doing' works... but usually if you do that they change it to, 'no, what job do you do' and you're back in the deathtrap...