TakeruK, Mathcat, Vene, you're obviously not veterans, so:
DROP! is an order to do pushups. It has many cultural meanings that movies like Private Benjamin, In the Army Now, or Full Metal Jacket, or anything involving boot camp or basic training can explain. It comes from the sensibility that pain will make you think. Someone needs to publish a drill sergeant quote of the day calendar.
The weird thing. It's pretty simple. In the military, a person has two names: their rank and their last name. You call people who are equal to you or beneath you in rank by last name or by rank, occasion