So, my dog ate a popsicle stick....

Oh crap! I've had my dogs pass some weird stuff before (Rags, glass Christmas ornaments, leather glove) but this doesn't sound good. Hopefully your dogs digestive juices are strong enough to render the stick flexible. If you see blood in his stool (black or red streaks), you've got a big problem. I would wait though. Dogs are pretty amazing when it comes to their healing properties.

Keep us updated.