Unpleasant notes are inventory items in Problem Sleuth. They are the three detectives' main method of communication before they join forces.
Problem Sleuth and Ace Dick have sent a ridiculous number of notes to each other, ended by Ace Dick's reading "Problem Sleuth is OK sort of". Pickle Inspector has only written , which is to Problem Sleuth. It informs Problem Sleuth just how impolite he is.