A trick requiring a friend and a younger pupil. Older Boy A would tell Younger Boy all about Older Boy B's fantastic piano playing grandfather. Younger Boy will listen because he is being spoken to by an Older Boy. Older Boy A will then suggest that Younger Boy approaches Older Boy B, as he is immensely proud of his grandfather, and will gladly tell you more. Younger Boy, to be fair, probably has no interest in Older Boy B's grandfather. However, he is being let into something new and intangible, and is probably thinking that having friends in the years above will make him immune to all forms of bullying. So he will approach Older Boy B, and timidly ask about his amazing grandfather pianist. Older Boy B has, of course, been fully briefed, and will throw an outrageous epi fit, screaming that his grandfather's hands were blown off in the war. Are you taking the piss? Are you fucking taking the piss out of my hero grandfather? Bingo - one tearful, terrified, confused and unhappy little boy. Result.