Three snails decided one day to have coffee at a hotel. Just as they entered the cafe, it started raining. The elder of the three snails said to the youngest: Go home and bring an umbrella.
The little one said, I will go provided you don't drink my cup of coffee.
We won't, promised the other two.
Two years later the big snail said to the middle one:
Well, I guess he isn't coming back, so we might as well drink his coffee. Just then, a little voice called from outside the door: If you do, I won't go.