My parents stay up late on the couch just chilling, and I have a small house so smoking with them awake anywhere is hard because they walk around. First off smoking a joint isn't ideal, it creates alot of smoke, hit the pipe or the bong instead. Try following these steps next time...
1. prepare everything in stages so if somebody walks in your not stuck there with everything sprawled out
2. think of a good place to stash it if you have to in a hurry
3. turn on some music not too loud, but enough to cover some noise
4. open a window or leave a window open
5. take long slow hit, cover the bowl with something and finish hitting it through so it doesn't leave smoke
6. go to window blow out smoke
7. take deep breath through nose, out through mouth out the window

There are all the steps I take when smoking in the house with my parents awake and moving around, even at night when its quiet.
~Bryan~