Green’s Dictionary of Slang

bundle! excl.

[bundle n.2 (1)]

(UK juv.) a shout that signifies that a fight is taking place.

OnLine Dict. of Playground Sl. 🌐 bundle (1) n. shouted whenever a fight was taking place (or in the disco when you were feeling bored) and involved everyone jumping on top of each other in a heap before scarpering when the dinner lady or a teacher came around the corner.