To the flat earthers, where is the edge of the world? Is it where we drew it on maps, somewhere in the Pacific ocean? If so, get on plane in LA and fly to Japan, staring at a compass the entire time to make sure you aren't going East. If that doesn't convince you, when you get to Japan, keep flying west to Russia, then keep going west to England, then west again to New York, then west again back to LA. You'll notice that you don't in fact fall off the earths edge at any point.
Make sure you don't take your eyes off your compass though, as the spherical earth conspirators will try and tamper with it.