vape pen, preloaded cartridges.
This is a good one too, but I doubt OP is going to get a hold of these cartridges if they don't even have a pipe.
However, if you do have the ability to get one OP, then do so. I've used them and they carry a light scent that can easily be masked. Someone close to me has vaped oil carts in their college class and no one noticed.