Lol.
Seriously though, if the Earth did have a black hole (presumably at the center) in it, every person on the planet would immediately know SOMETHING was wrong because you'd feel like you weighed a ton due to the sudden surge of gravity.
Until then it'd be a matter of time before we'd all be sucked into a singular point of nothingness. It'd probably take a couple days or so, but then again, there wouldn't be any more 'days' because I'm pretty sure the Earth would either stop rotating altogether or would drastically slow down.
In the meantime I'd suggest banging as many people of the opposite sex as you could (or same sex if you had any gay fetishes you wanted to act on), if you could find the strength to do it.