A bloke takes his blind pal for a spin in his plane but dies of a heart attack at the controls.
Realising what's happened, the blind guy finds the radio & says "Mayday. Mayday. I'm a blind man alone in a plane, the pilot's dead & we're flying upside down."
Air traffic control say "OK sir, but if you're blind how do you know you're upside down?"
Bloke says "Coz the shit's running down my back!"