It was the custom of the boys to stop it with a mushroom when enemies were in the neighbourhood.
Not only smoke came out of it.

There came also children's voices, for so safe did the boys feel in their hiding-place that they were gaily chattering.

The pirates listened grimly, and then replaced the mushroom.
They looked around them and noted the holes in the seven trees.
"Did you hear them say Peter Pan's from home ?" Smee whispered, fidgeting with Johnny Corkscrew.
Hook nodded.

He stood for a long time lost in thought, and at last a curdling smile lit up his swarthy face.

Smee had been waiting for it.
"Unrip your plan, captain," he cried eagerly.
"To return to the ship," Hook replied slowly through his teeth, "and cook a large rich cake of a jolly thickness with green sugar on it.
There can be but one room below, for there is but one chimney.