That has definitely not happened to me, but I can't wait until a horror film decides to use a possessed Echo as a plot device.
@OP: Better don‘t watch ;)
There was an awful case about three years ago where some guy hacked into a baby video monitor and started yelling at the 10 month old child: http://time.com/79170/stranger-hacks-into-baby-monitor-and-s...
I think as IoT spreads we're going to be seeing some real life horror stories unfortunately. These devices are just barely secure at the best of times and I don't think their network stacks are anywhere near tight enough.