Found this on another site
A couple in their nineties is having problems remembering things,
so they decide to go to the doctor for a checkup. The doctor tells them
that they are physically okay but they might want to start writing things
down to help them remember.
Later that night, while watching TV, the old man gets up from his
chair. His wife asks, "Where are you going?"
"To the kitchen," he replies.
She asks, "Will you get me a bowl of ice cream?"
The husband says, "Sure."
She gently reminds him, "Don't you think you should write it down
so you can remember it?"
He says, "No, I can remember that!"
She then says, "Well, I'd like some strawberries on top. You'd
better write it down 'cause I know you'll forget it."
He says, "I can remember that! You want a bowl of ice cream with
strawberries."
She adds, "I'd also like whipped cream. Now I'm certain you'll
forget that, so you'd better write it down."
Irritated, he says, "I don't need to write it down. I can remember
that! Ice cream with strawberries and whipped cream!"
He then grumbles all the way to the kitchen. After about 20
minutes the old man returns from the kitchen and hands his wife a plate of bacon
and eggs.
She stares at the plate for a moment and says, "Where's my toast?"