Submarines.
They are both at the bottom of the ocean full of seamen.
A submarine!
The Navy blues What part of the Mac's desktop would seafarers miss when at sea for a loooong time The Dock
A Snailor
Mom: It's a private caller. Dad: Don't answer that. We only pick up for ranks Lieutenant Caller and higher.
Count the stripes on his track pants.
Nobody ever says "Thank you for your service" to the latter.