ouch. well, she's not giving you much, and you don't have much to work with. Don't worry about upsetting her. You don't want to be a slave to a girl you don't even know.
Honestly, I don't have a good feeling for where to take it. I'd probably mess it up. She's in an unknown state right now. My first inclination would be to terminate the interaction and pick it up later. Either by saying nothing, or something abstract.
"I'll just leave 'funny' up to interpretation."
I'd probably say saying nothing is better. Then resume in two or three days like the conversation about FB pictures and "funny" didn't even happen. Gives her time to reset or wonder where you went, and you time to think / remember something about her or your evening.