Let's say you're a talented IT admin at a large company. You want to get revenge if you're fired. You set up a script that checks your account every couple of weeks and makes sure you're still enabled and logging in.. if this script detects your account is disabled or hasn't logged in in a month, it triggers.. Then it goes and deletes all the customer data destroying the company.. Well that would be a dead man's switch in a basic usage. Now take that scenario and apply it to other things. Like instead of a script it's a few people checking on you.. or instead of deleting customer data it releases a video... Etc..