Just the other day, I went to go fishing at a sky island near the end of the world for an Angler quest. I must've AFK'd or something, because I triggered a Martian Probe and spawned the Martian Madness event. I figured they'd only spawn if I were at spawn, but there was 1 other person on the server hanging out in spawn, so a whole bunch of stuff was attacking me. Saucer shows up, I decide to teleport home.
Now, at this point, I thought the Martian Saucer had despawned. It wasn't appearing on the map, after all. I'm just sorta standing around in the spawn house, getting ready to throw my sentry minions outside, when suddenly the Martian Saucer ascends from below at mach speed and instantly slaughters the Guide. Before I could even register what happened, it was gone, and bits and pieces of the saucer (its gibs) started falling from the sky. Even after a thousand hours in this game, it still finds new ways to catch me completely off guard.