At the burning tip of a blunt, when it starts to burn down farther on one side than on the rest of the blunt, it is canoeing. This can be fixed by wetting a fingertip with saliva and dampening the burned down end. This is not only with blunts either. This can easily happen with joints and it happens with cigarettes sometimes too.
Dammit Elliot! Fix the canoe and then pass that blunt to Hernando.