Butt Can

When people ask about my army service, I tell them I spent years in the 4216th Mess Kit Repair Unit. We were part of the old brown boot or black boot army--I no longer remember which, although it used to matter. 

We lived in wooden barracks back then,  so we set a fire watch at night. That was no fun. To pass the long nights, we told one another yarns. You had to stay awake and look for fires. But you could smoke cigarettes and talk.

The unit had big old tomato cans hanging from interior posts. These cans were half filled with water. You were supposed to drop your cigarette butts in the cans or spit in them if you wanted. Then, if you were man enough, you could pick up a can and drink it in front of your friends. Hence, "A butt can a day keeps the doctor away."