A joke

One day Sue went to the swimming pool with her grandparent and her brother.
They started to play with the ball and something like that. After a long time, they went to the dressing. When Sue entered saw that somebody had stolen all her clothes and she only had the swimsuit.
She quickly went to talk with her grandfather. Her grandfather said that the only option that she had are to went with his jacket, the trousers of her brother and the sandals. And Sue did this.
When they were going outside of the swimming pool, Sue saw all his friends with her clothes.
His friends had made a joke, but Sue spent a very embarrased moment.