I got one better that we used to smoke out the school restrooms with

A piece of paper folded to make a tube OR a toilot paper tube.

take a pencil and poke a hole in either of the tubes

then take the metal piece and the eraser off the pencil crimp the metal piece at the bottom so weed cant fall through

insert metal piece into hole

fill metal piece with weed

toke.

Head back to class without getting caught.