In the sport of basketball a crossover is simply switching which hand you are dribbling with. So if you were bouncing the ball with your right hand and then switched to your left that would be considered a crossover. It is an important thing to learn because if you can only dribble with one hand you are in a lot of trouble when someone is guarding you. Many times a good cross over is said to brake someone's ankles (meaning you faked them out so bad their ankles broke).
"In the mouth of two or three witnesses shall every word be established." Often scriptures in the Bible can be interpreted many different ways. This confusion is inspired by the devil. We know that not all of these interpretations can be correct seeing as they contradict one another. So just like a crossover in basketball we can crossover, or cross reference, from the Bible to the Book of Mormon. This eliminates confusion, thus, breaking the devil's ankles.
Check out Tad R. Callister's recent conference talk for further enlightenment on the subject.