i have a can from some canned vegetables or some shit. It's perfect, tip the joints/blunts in there. I always kill the shit my bong and then dump the water out in a couple days.
if you dont got a ashetray dude, get a plastic cup, fill it up a little over a 4th of the way with water, and ash in that. the water is so no holes get burnt in the cup. then if you wanna dispose of it fill a little coke in there or any kinda dark soda, and pour it in the trash. it will cover the ashes if you get that paranoid bout gettin busted. thats my ideas.
We use this pretty ash tray we just leave on the desk. Nobody ever sees it. I even leave my pipe next to the computer. Sometimes the best place to hide something is right in plain sight. No one would ever expect it to be there. And half our stuff is in a basket right on the desk. Never had a problem.