BobStaMan,
"The game is never over until the 21'st out is made." Last time I checked there are 42 outs in a regulation high school game.
There is not a single reason for an umpire to allow you a timeout. The umpire may grant you a time out, if he feels it necessary.
As pizza_ump said, hold your hand up, step out of the box, without time being granted,it is a strike. If the pitcher throws a strike, that 2 strikes called on the batter. One for stepping out of the batters box without time being granted, and one for the pitch.
Also, if you try to call time out for the purpose of causing the pitcher to balk, and in the umpires judgement it was a deliberate attempt, you can be ejected from the game.
Game management is the responsibility of the umpire.