I'm assuming you're joining army, I'm going to tell you about their drill instructors. Drill instructors in the army aren't as insane as you think, you have room for error in what you say and do, but still try not to get them too mad. Make sir you don't call them "sirs," because they're not, they're enlisted. However if you're joining the Marines you can't get them a little mad, can't make the wrong move (if you slap a fly while being inspected the make you find it and hold it out for like 20 minutes), don't say the wrong thing in front of them, definitely [b]DO NOT[/b] call them sir, let then call you any nickname they want, and most definitely do not call them a drill sergeant. They are not drill sergeants, they are drill instructors, and Marines hate being called or associated with things they're not.