Trick to switch off phone even when locked

Hi, I am gonna share this trick through which you can annoy anyone who has kept a password lock on their phone. I do the same to my sister.
Note: This trick is only for LG phones which do not allow any function of the end key when locked. Other phones have no such restrictions. I have tested it on my sister's LG P350 Optimus ME.
So here's the trick:
1) On lock screen, slide the unlock slider.
2) Click on the the Emergency Call button.
3) Now on dialer screen press and hold end key to get the turn off menu.