He's about to kill some Lunglings

Back when I smoked I liked the carbon filters they sell. There are silicone pieces that hold the joint on one side, a screen in the middle, and a filter on the mouth side. It was a lot smoother than plain smoke but the filters clog fairly often. IIRC Actitube was the name brand.

I think they just mean a crutch. The only thing they filter is chunks of weed though.