When toking from a bong, one must hold a lit lighter to the end of the chalice, put his mouth to the opening at the top of the bong and breath in to draw the smoke up and into the chamber. The process is referred to as 'milking the chamber.' Once the chamber has been milked appropriately, the toker takes his thump from the rush hole and breathes in HARD, sucking up a sweet blend of air and smoke which may give him a harsh headrush.
"Dude, you milked that chamber nicely, now take yo' thumb off the rush hole and BREATHE IT!!"
by Rep August 24, 2004