"3" qualified
 

Back in the sixties the prefix/suffix "3" stood for Special Forces Qualified.

One day Johnny was in the back yard playing soldier. He had his dad's beret on and Lucy saw it. Lucy asks if Johnny is "3" qualified. And Johnny says Yes.

Can you skydive she asks. Yep, I jump every weekend.

Can you skin dive? she asks, and Johnny says yep, I go to Key West every summer.

Lucy thought that was pretty neat so she lifts up her dress and says DIVIE IN!! Johnny turns all red and gulps and says: :Er, I was just kidding about being "3" qualified.