So I was thinking about this a few days back and haven't come up with what I would call a for sure good way to animate a stretching tongue and still apply physics. The two thoughts I had are:
1) Create some class derived of SPQuad and tween the width and rotate the box so the new ends of the rectangle now are in the correct locations if need be.
2) Create a class for the "tip" of the tongue and tween the position of the tip, while creating a path from the start to the finish. Then filling that path repeatedly with a graphic that would represent the middle part(s) of the tongue.
Anyone have any thoughts or maybe have tried something along these lines before?