a friend of mine had her bong smashed by some random guy about a week ago, and he immediately forked out $50. i think any real weed smoker would automatically do something along those lines, but if your roomy doesnt smoke much i wouldnt say i would expect it, or that it would necessarily even cross his mind that he should definitely at least put something towards a new piece. id give him a few days, and if he does nothing towards it id raise the issue in a normal sort of way. i wouldnt bother pushing the issue, its just a piece after all, besides its always fun to replace them unless its a special one.
