Why do cemeteries have fences?
Because people are dying to be there.
Alright listen up, chucklehead. This joke is funny because it uses the phrase "dying to be there" in two different ways. First, it literally means people are dead and buried in the cemetery. Second, it's a figure of speech meaning people really, really want to be somewhere. So, cemeteries have fences because the dead people are, well, dead inside them, and also because living people might REALLY wanna get in there, get it? I know you don't, but that's okay, you're not the sharpest tool in the shed.