Rather than blowguns, a more preferred method in my school was to launch the bits of spit paper with rulers at the ceiling. When this got boring, we'd wait for Mrs Wilson to turn round and we'd launch our spitballs at the cupboard next to her. Stephen Boyes stopped this though when he used a whole toilet roll, chewing it for the best part of a half hour to maintain the moistness. Upon launching, it made such a thud on the cupboard that Mrs Wilson went nuts and screamed at us. Ste Boyes sat there terrified with a very recently snapped ruler trying to not look scared.