Two GIs in the Vietnam war have been stuck in a trench for three days when one needs a shit.
- I can't go in here, it's really going to stink.
- There's another trench over there.
- I'll cover you with the M60... just give me a shout and I'll cover you so you can get back.
- OK.
So the GI runs across while the other fires off the machine gun.
He's waiting 10 minutes... 15... 20... he shouts out:
- Are you OK?... nothing.
Over an hour later he hears his mate shouting.
- Cover me, I'm coming back!
When he jumps back in, his mate says:
- Where the fuck have you been? You've been gone for over an hour.
- Yeah, I know. There's a girl in there, I played with her tits, fondled her arse, turned her round and fucked her from behind!
- It was great!
- You lucky bastard - said the other.
- Did you get a blow job?
- Nah - said the other, disappointedly.
- She didn't have a head.