Where's my like button? Lol.. I let Roller play with 20 oz and 2 liter bottles as well, but I make it a bit more exciting for him. I put a handful of kibble in the bottle, and stuff the neck with peanut butter, and let him entertain himself, getting his kibble out (after he licks a hole in the peanut butter) and then once he's done all the possible damage he can, or I get tired of hearing the bottle crash around (which ever comes first), then I take it away from him and he usually goes to sleep afterwards lol.