here's an idea:

forget about the bong. use something smaller like a pipe, and if you don't have one, improvise. smoke small bowls. really small bowls. put in as much weed as you can get in one hit. the bud should be completely gone at the end of the hit, so it doesn't burn (and release smoke) when you're done hitting. it'll help reduce the amount of smoke. your lungs will get rid of some of it too. use some kind of filter (toilet paper roll stuffed with dryer sheets maybe? we called it a "wookie") when you exhale. you should have virtually zero smoke, and much less smell.