Sir Sandwich

Sir Sandwich

This joke appeared on Everybody Loves Raymond and I don’t get it:

Our drill sergeant stressed to us the importance of addressing all officers with what he called a “Sir Sandwich.”

“Sir, yes Sir!” “Sir, I don’t know, Sir!” and the like. A few days later a colonel approached me in the motor pool and asked me what I was working on.

Using the Sir Sandwich I said “Sir, checking the oil, Sir, in these jeeps, Sir.”

And “Sir, checking the tires, Sir.”

The colonel laughed and said “Private, I appreciate your respect but I don’t need a Sir Club Sandwich.”

So can anyone please explain the punchline?