out of left field

unexpectedly, suddenly and surprisingly

Strange, and unexpected. Lucky/Unlucky.

Most baseball batters are right handed (therefore swing the bat from right to left) and hit a ball out into left field.
The batter immediately drops the bat and runs to the right to get to first base.
It is quite difficult for a good left field ball to hit the ground in far left field, get picked up, and thrown, accurately across the entire field to the first baseman, before the batter can get to first base. If this does happen, its an incredible throw, from way out in left field. Totally unexpected.

some kind of baseball slang referring to an unexpected event.

(help me out here UDers.. where did this phrase come from and what does it really mean?)

1) a person who doesn't really have all his/her marbles, 2) s/he is kinda weird, 3)comes up with the craziest ideas, 4) see loco

out of left field comes from when wrigley field was first built. In left field there was a insane asylum so when something crazy or unforseen happened it was termed, "out of left field"

What you do when someone tries to make fun of you for whatever reason it may be, Such as where you grew up, where you live/how you live, etc, and then agreeing with it and then running way out into left field with it, this usually requires you to think really outside the box and generally use any stereotype you can come up with that relates to your situation and then making the situation just so extremely out there that it makes barely any sense. (Try to make people realize how retarded they sound by saying the stupid shit they say)