I partake (don't worry I keep it away from the birds), and it shouldn't harm your birds if they are not in the same room. If you can't get him to stop at all, and if you're very concerned, put something down on the door like a towel. However, I think your birds should be fine if they're not in the same room since smoke would have difficulty reaching under the door. Think about it - it has to rise after sinkning under the door slit, so it is improbable that large amounts are reaching your birds.
Furthermore, if he's just some college student he probably isn't even smoking enough to really do damage to the birds since it's expensive. I don't know the full situation though. The smell itself won't harm them and VERY strong (makes you think there's more than there actually is), it's the smoke that's the problem. So you will be annoyed but your birds are probably fine imho. Just don't let him puff in their faces or smoke up the room that they're in - this is what leads to irritation.
It's definitely not like teflon though in terms of toxicity. Remember - smell isn't an accurate indicator of danger - burning teflon is odorless and deadly, while marijuana gives a very strong stench but nowhere near as dangerous.
That must be incredibly annoying though. The smell is very potent, and if you weren't a fan... well let's just say I wouldn't be happy either.
I've seen birds that were abused by potheads though. It's really sad. This poor cockatoo was in a small cage and it was exposed to a constant miasma of thick pot smoke. Poor thing must have been irritated all over its skin. Of course it was a plucker. Now its basically damaged for life. It's a real shame that they have to ruin everything for people who show respect for other living things.
