when one takes a roach and sticks it in a bong and then proceeds to put bud all around the roach like a moat. Smoking the roach then lights up the surrounding bud when it gets to the bottom.
The moat is a body of still water. It has been known to contain many stolen shopping trolleys, and, as the rumour has it, a dead body, and Syphilis. It is often drank by Menzians.