I've used the trolley problem a lot, at first to show off my knowledge of moral philosophy, but later, when I realized anyone who knows any philosophy has already heard it, to shock friends that think they have a perfect and internally consistent moral system worked out. But I add a twist, which I stole from an episode of Radiolab (which got it from the last episode of MASH), that I think makes it a lot more effective; say you're the mother of a baby in a village in Vietnam, and you're hiding with the rest of the village from the Viet Cong. Your baby starts to cry, and you know if it does they'll find you and kill the whole village. But, you could smother the baby (your baby!) and save everyone else. The size of the village can be adjusted up or down to hammer in the point. Crucially, I lie at first and say this is an actual historical event that really happened.

I usually save this one for people who smugly answer both trolly questions with "they're the same, of course I'd kill one to save 5 in each case", but it's also remarkably effective at dispelling objections of implausibility and rejection of the experiment. I'm not sure why this works so well, but I think our bias toward narratives we can place ourselves in helps. Almost everyone at this point says they think they should kill the baby, but they just don't think they could, to which I respond "Doesn't the world make more sense when you realize you value thousands of complex things in a fuzzy and inconsistent manner?". Unfortunately, I have yet to make friends with any true psychopaths. I'd be interested to hear their responses.