Why do short cowboys aim for the knees?

Hey all,
To answer the question posed within the title of this post I say...to get you (the reader) to actually stop click, click, clicking away into the oblivion of the Internet and read this post...gotcha sucker. Well why you are here you might as well give me two good and opposing reason why short (under four foot) cowboys always aim for the knees? Maybe it's cultural? Maybe it's functional? Maybe it's a bad rumor and your ashamed to hear that I'm spreading this stigma. Please give me something that will entertain me for thirty seconds. Thirty seconds is all the time I have before my hummingbird attention span and demanding boss kick me off of this sight and onto another boring task. I leave you (the reader) with this question and image, what is the best (as in most awesome) way to paint a building? Kevin's answer is a series of dive bombing hawks trained to carry water balloons full of paint. This theory could also work with siding, which is even more awesome if the Hawks can find a way to make it stick.