After a Halloween party with four guests:
- All guests took a coat and a hat of another guest (i.e., every one took a coat and a hat but not their own).
- No guest took a coat and a hat from the same person.
- A took the coat of the person whose hat B took.
- B’s coat was taken by the same person who took the hat of A.
- C took D’s hat.
A took B's hat and C's coat B took C's hat and D's coat C took D's hat and A's coat D took A's hat and B's coat