Great thread!
a variation of, "Does a bear shit in the woods?" that my dad uses often. " Does a zoo bear shit on concrete?"
My grandfather used to recommend chicken shit for chapped lips. When asked why he'd say, "You won't be licking your lips."
"Dumber then a brick bat."
For some military ones...
"Its FAC out here today." FAC= Flat Ass Calm, referring to the sea state.
To a new sailor, "Go down to the DC shop and get the DC punch." When the sailor got there the Damage Controlman would punch them...
To new sailor, "Go get the keys to the sea chest from the Captain." Depending on the CO this one could go on all day. The CO might say, "I gave them to XO." Then the XO would continue by sending them on to someone else.
For a disheveled looking sailor, "You look like 10 pounds of shit in a 5 pound bag." Or, " Did you dive on a wrinkle bomb to save the crew?"
I had a salty Senior Chief who always made us do maneuvering boards (a reliable predictor of how ships course and speed will play out over time). Anyway, I remember him yelling anytime he got one that looked too busy, "Two f@#king lines!" That phrase became useful when anyone over thought or over did anything.