Sister Catherine was asking all the Catholic school children in fourth grade what they want to be when they grow up.

 Little Sheila said, "When I grow up, I want to be a prostitute!" 

Sister Catherine's eyes grew wide and she barked, "What did you say?!" 

"A prostitute!" Sheila exclaimed.

 Sister Catherine breathed a sight of relief and said "Whew! Thank God! I thought you said 'A Protestant'!"