Warnings issued by the U.S. military to their own troops:

"Aim towards the enemy."
Instruction printed on US Rocket Launcher.

"When the pin is pulled, Mr Grenade is not our friend."
US Marine Corps.

"Try to look unimportant; they may be low on ammo."
Infantry Journal.

"Five-second fuses only last three seconds."
Infantry Journal.

"If you see a bomb technician running, try to keep up with him."
USAF Ammo Troop.