I used to have the dancing Coke bottle. Looked EXACTLY like the 6 1/2 oz style. I had it displayed between several real full bottles on top of a Coke machine in my store.
When people would come in, as we were talking a certain voice tone would activate it momentarily.
Out of the corner of their eye they would catch the movement! "I think I just saw that bottle move" I'd say "what? I don't believe you"
It was a lot of fun and then when the little kids would clap their hands the bottle would dance and they went nuts!