A student, after the first anatomy course at the Fac, realizes that almost all words end in "us", such as: radius, ulna, humerus, etc.
Arriving at home, she likes to call everyone by putting at the end of each name "us".
Paulus for Paul, Ericus for Eric, Ruthus for Ruth, Chantalus for Chantal and Audus for Aude.
As she has forgotten that her name is Anne, her little brother Paul asks her: "But how are we going to call you? ". Everyone is looking at each other.