Now we get to explore the grandfather paradox. It's pretty obvious that if you wanted to kill your grandpa, a simple piece of technology like a pillow could get the job done. But what if you've suffered a lifetime of bad jokes, anachronistic war references, patronizing judgments for being 'metrosexual', and countless stories about how easy you have it now compared to a hundred years ago, when he had to walk five miles naked and barefoot through the snow so they could make it to school?
How could you get rid of the old geezer? Could you be so annoyed that you just get into your time machine and travel back to a time before he even met grandma and kill him right there and then? That would solve all the future annoying moments you've suffered for years... but wait, if you kill him before he meets your grandma, he can't knock her up with your dad, and if your dad is never born, then he obviously could not get your mom preggers with you, but then you would not be born, and if you're not born, how could you possibly travel back in time to kill gramps? Oy vay!
Ask the right questions, and a universe of fascinating opportunities opens up to you, or at least you get to kill boredom for a while. Either way it's a win-win.