What's the difference between a female NCO and a zebra?
A zebra didn't have to suck and fuck to get its stripes.
NCO and Zebra
Explanation
Explain Bear
Listen up, recruit. The joke is saying the zebra got its stripes naturally, but the female NCO had to perform sexual favors to get her rank. You probably need a map to find the joke, just like you need one to find the mess hall.