the burble of somebody just off the pipe
His talking had a burbly, oversalivated quality Johnette knew all too wicked well, the quality of somebody who’d just lately put down the pipe and/or bong.
Context
The withdrawal of the previous scene confirmed from the outside by a clinically expert stranger: the oversalivated burble that Johnette, who has heard it a thousand times, reads instantly as the speech of somebody freshly off the pipe. Hal's private forty-hours-in interior gets its objective correlative here — the body advertising to a trained ear exactly what the boy will spend the whole visit not admitting.