out of left field 

unexpectedly, suddenly and surprisingly

He just came up with it out of left field.

out of left field by The Return of Light Joker August 22, 2008

out of left field 

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.

This lead is right out of left field; it'll be crucial in catching the thief.

out of left field by the intolerant March 28, 2016

Out of left field 

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 happened?
I don't know... i didnt really expect that, it was just like, out of left field, just crazy it blew me away

Out of left field by Hugh Jerrection April 9, 2009

out of left field 

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?)

What happened?
I don't know... it came out of left field.

out of left field by Urban Newbie September 15, 2007