Military Joke

A LT walked up to a SGT jumping up and down on top of a manhole saying the number 3 after every jump. The LT yelled What are you doing SGT? Nothing Sir just seeing how high I can jump while on this manhole. The LT shook his head and said Well that's not high at all. Get out the way and let me show you how to do it. The SGT moved and the LT jumped real high in the air. As he did the SGT removed the manhole cover and the LT fell down into it. He then replaced the cover and started jumping again saying 4, 4, 4.