You could show them the bubble primer on this site, then point out that with credit tightening there is no more ‘air’ (as it were) left.
Get them a copy of ‘Crash Proof’ by Peter Schiff, as well.
Something to point out (that keeps me optimistic), is that since SD was on the forefront of the bubble it should also be the first to correct. So if they can keep their job, find a nice rental, sit back and enjoy the weather.