Zamkněte jim dveře a dejte jim klíče do láhve s vodou, kterou pak strčíte do mrazáku - ale nikdy jim nelepte jejich věci na strop více než dvakrát.
Lock their door and put their keys in a glass of water, which you then put in the freezer - but don't Blu-Tack their possessions to the ceiling more than twice.