Aye, it's already been invented.  First you flash the bright lights
repeatedly while the other Vanagon is still off in the distance.  As they
approach and their body outlines become visible you rapidly flap both arms
like a drunken monkey.  When you can see their faces you start screaming and
jumping up and down in your seat high enough to hit your head on the roof.
As they pass and look at you in condescending-you-forgot-the-prozac sort-of
way you roll the window down and hang the left half of your upper torso
outside and wave at them again just to make sure they know you're on the
Vanagon list.

Since I live in a Vanagon-deprived area of the country such behavior becomes
quite involuntary.

Chris S.
'85 Westy
www.knology.net/~vw/
http://groups.yahoo.com/group/wolfsburg_campers