Bloody Bogies. When you pick your nose and you pull out a red one.
when you pick your nose and you pull out a bogie with blood on it (and i mean a real slimey squiggy bogie all bloody) keep it on your finger but dont show anyone. Then, go up to your mate and say "ive got B B's" he/she will reply in confusement "what are B B's?" you then shove your finger with the bloddy bogie on it right infront their face and say "Bloody Bogies" (in a loud, childish and querky manner) then wait for the responce.