/kill ing yourself freezes the game

The title is self explanatory. When I /kill myself, the game gives me no response, and I have to restart the game.

EDIT: Apparently I / k [tab] [enter]ed or / k [tab] [space] [tab] [enter]ed and the system auto completed /kick instead of /kill. The real problem is that server op commands can be executed in single player(no LAN).