I was just thinking about some movie devices I've seen.

"This device reads my heartrate. If my heartrate drops, the bomb explodes."

Imagine knowing your family is just waiting for you to kick the bucket to swoop in on your inheritance. If such a device existed, it would be the perfect death troll. Don't give them any money while you're alive, and the device blows up your house/money/whatever you've wired once your heartbeat stops.