(Hope this works - it's two decades since I've seen this film!)

That weed was strictly forbidden in the school – so much so that it wasn’t even a written rule, merely Understood – and that Mr Keating probably smoked his fair share of it was enough to entice them to try it when the rest of the Society was gone. Knox took a deep drag and tried vainly, but with much bravado, not to cough; his eyes bulged and his hand shook when he passed the joint to Charlie, who laughed and took his own deep toke and closed his eyes.

As Knox expelled the acrid, burning-leaf smoke, Charlie heard him breathe a weak but triumphant, “Yawp!”