in (the) service

A crusty old Marine Sergeant Major found himself at a gala event hosted by a local liberal arts college. There was no shortage of extremely young idealistic ladies in attendance, one of whom approached the Sergeant Major for conversation.

"Excuse me, Sergeant Major, but you seem to be a very serious man. Is something bothering you?"
"Negative, ma'am. Just serious by nature."

The young lady looked at his awards and decorations and said, "It looks like you have seen a lot of action.
"Yes, ma'am, a lot of action."

The young lady, tiring of trying to start up a conversation, said, "You know, you should lighten up. Relax and enjoy yourself."

The Sergeant Major just stared at her in his serious manner. Finally the young lady said, "You know, I hope you don't take this the wrong way, but when is the last time you had sex?"
"1955, ma'am."
"Well, there you are. No wonder you're so serious. You really need to chill out! I mean, no sex since 1955!"

She took his hand and led him to a private room where she proceeded to "relax" him several times. Afterwards, panting for breath, she leaned against his bare chest and said, "Wow, you sure didn't forget much since 1955."

The Sergeant Major said in his serious voice, after glancing at his watch, "I hope not; it's only 2130 now."