Bob, bob, bob. You already know in your heart what to do… 
Use proper names and brand names to overcome the “we don’t know any words” problem.
Pick five words. Maybe:
HE ‘drink’ (straight, level high gesture like the “drinking problem” joke where you indicate you’re trying to drink through your forehead – it’s 1st tone after all, and this is memorable)
pIjiu ‘beer’ (upward motion of popping the tab top, then a low motion dropping the tab on the ground – not downward, this is 2+3 tones) (and for “standard” Chinese with a neutral tone, the upward tone on the pI is enough really). It’s easy to remember because if you drink too much beer, “you gotta pee, Joe!”
Qu ‘go’ (moving one’s hand downward from the nose as though someone has sneezed works well for me – because ‘people always go away when you sneeze!’)
Yao ‘want’ (I always use the “claw hands, palms inward, starting at eye level and drawing straight downward” gesture but that’s just me)
meIyou ‘doesn’t have, there isn’t’ (this gesture is really dumb – it’s an upward scraping in an imaginary mayonnaise jar – get it? meIyou mayo? Have no mayo? I know, I’m killin’ ya…)
You will find that ‘bu4’ or ‘bu2’ for “not” or the negation doesn’t really need to be taught – a big negative shake of the head plus whatever verb you’re pairing it with is just fine.
Find a simple story. Something like:
Bob drinks beer.
Bob wants beer. Bob wants to drink beer in/at [local place]
Bob has no beer.
Bob goes to [local place’s] 7-11.
7-11 has no beer [=“there is no beer in 7-11” pretty much; this is Lesson 1, don’t sweat the locative ‘zai4’ too much, just throw 'er in when needed and usually no one will agonize over it]
Bob wants beer! Bob wants to drink beer!
Bob goes to Paris. In Paris there is a Wal-Mart. The Wal-Mart in Paris (“Zai Paris de* Wal-Mart” – slip in those grammatical functions where they’re easy to figure out) has beer.
Bob has beer!
Bob drinks beer in Paris.
Then, of course, milk the story…what brands of beer does Bob drink? Which brands doesn’t he drink? Does he drink in Shanghai? Does he drink in Taibei? Does he drink beer in [local place]…etc. etc. ad nauseum etc. remembering that your listeners find every sentence fascinating (well, at least insofar as they find they can understand Chinese, a fact they never knew about themselves before) and even though you find these sentences amazingly easy, they don’t, and need to hear them over and over and OVER with, of course, minor but fascinating variations.
Then ask the questions…every question you can think of. (OF course for the family class, this may not be necessary or desirable). Be sure to have a fixed gesture for every WH- word – it’s really important for students to nail these early on, and being asked so many questions definitely helps. Anticipate problems with confusing sheI and sheNme (just as ‘quien’ and ‘que’ get confused in Spanish learners.)
I do this story every time I need a quick ‘demo’ type experience. My cousin, who is in his early 60s and has dyslexia, can still remember the word for “beer” immediately when asked, and this is three years later.
Rinse, lather and repeat. Many times.
