Leave it.

You leave the painting leaning against the wall and set off walking at a brisk pace. You've only travelled a short distance, however, when a tall, heavily-built man steps out in front of you.

He points a large, bloodied knife at your chest. "Hand it over," he says.

You can:

Look behind you in case his accomplice isn't there weilding an equally big knife.

Try to fight your way past him.

Say, "Sure, it's three blocks that way", pointing in a random direction.

Say, "I left it propped up against that wall back there".