Hurrah for someone else who doesn't know about cricket, which has to be the most boring game in the world after baseball.
(says he, hastily digging himself a blast-proof shelter that is unasailable from all directions! )

LBW = Leg Before Wicket

If you prevent the ball from striking the wicket by getting your leg in the way - whether accidently or on purpose. If the Umpire calls this, then you are "out."

Why such a sensible defense should be penalised is beyond me - but then , so are most of the arcane rules of cricket.

I mean - it takes courage to put any part of your body in the path of a cricket ball; harm can come to a young lad like that. Courage in the interests of keeping your team in the game should surely be rewarded?