I know I'm dead
An elderly couple is lying in bed one morning having just awakened from a good night's sleep. He takes her hand and she responds, "Don't touch me!"
"Why not," he asks.
She answers back, "Because I'm dead."
The husband says to her, "What on earth are you talking about? We're both lying here in bed together and talking to one another."
The wife says, "Not so, I'm definitely dead."
Her husband insists, "You're not dead. What in the world makes you think you're dead?"
His wife answers, "I know I'm dead, because I woke up this morning and nothing hurts.