On some Android phones pressing the power button 5 times in a row will call emergency services. I learned this the hard way when I was very drunk and fumbling with my phone - cue a call back from 911 where I had to awkwardly explain in the middle of crowded bar that the call was made accidentally.

If you have a young child you may want to consider disabling this feature as it's very easy to accidentally trigger and law enforcement is required to respond if they don't receive and intelligible response!