The real kicker is how "kicker" became a slang term for the most surprising or unexpected revelation. Of course it is found in sports lingo, considering it does involve a physical motion, but the term actually has its roots in journalism.
In newspaper print, a "kicker" is the line above a headline that is meant to provoke interest in what's to follow. Over time, that interest-provoking lead-in became an actual word used to describe the most persuasive argument in a sentence (as in, "And here's the real kicker").
In Texas, the word has some alternative meanings as well. It's used to describe a Texan associated with Country Western apparel or attitude, or less benevolently, a redneck. And it's apopular radio station in the state as well.