A old lady and old man were sitting on their porch

One day an old lady and an old man were sitting on their porch when the old lady says “Hey pa, why don’t you run down to the restaurant and get us some ice cream.”

Pa said, “OK I will go right now.”

Ma told him that she had better write it down for him, because he always forgets.

He said no he would be fine, so off he went to the restaurant.

When he got back he handed her a hamburger and she said “Dang it pa, I knew you would forget, I told you to get mustard on mine!”