I can tell you one to join the Air Force. This came from a friend of mine who is currently on active duty, so I figure if he told it to me, I can pass it along.
There's a base in the middle of Iraq. And all four branches of the military are stationed there.
The Marine says, "oh, man. This is great. I've been sleeping in a leaky tent for 30 days. God, it's nice to sleep in a place with a roof over my head."
The Army soldier steps out the shower and says, "God, this is so cool. Hot water. I've been taking cold showers for the past 30 days and does it ever feel good to have warm water."
The sailor sits up in his bunk and says, "Man, it is so nice to have a bunk that I can sit up in without banging my head. And how cool is it to not have to have my head right next to someone's feet!"
The Air Force guy grabs the remote, pushes a few buttons and says, "What the hell? No cable?"
Don't kill me, Mike. It came from another guy wearing railroad tracks.