First time I cleaned out the smoker after smoking some baby backs I pulled the foil out of the bottom of the smoker and from the cover of the fire box and threw it in the trash can. A couple of hours later our Miniature Schnauzer, Bruno threw up on the living room wood floor. The vomit was full of tiny pieces of aluminum foil and some yucky oily fluid. Bruno had found the trash can and ate all the drippings and a bunch of the foil.
My wife got scared and took him to the emergency vet clinic. They did some kind of scan of his stomach. They didn't find much of anything there, but charged her $300 for the exam. For the next two days I picked up all of his poop, put it in a baggy with hot water and dish soap to liquefy it and then ran it through a screen. Found a little foil, but by the 2nd batch didn't find anymore foil.
Dogs will literally eat anything. I'm a lot more careful about making sure I get the foil in a secure trash can so Bruno can't get to it.