Those two both result in accidental 999 calls from people's pockets, but make it easier for people who've just lost both hands in an accident to call an ambulance. My phone had exactly three nines on the screen at least once.

I think the best way to have it do that is for the unlock buttons to be separate from the actual keyboard and sunk into holes in the sides.

See also my regular rant about why bicycle lights don't have some sort of locking mechanism so that they don't turn on when you put one thing on them in your bag and run out their own batteries/allow your bag to do a good impression of the video for "Danger Danger High Voltage".