So i had this idea of something a pet can swallow, and have it expand in his\her stomach(be impervious to stomach acids somehow) and expand it inside. if they misbehave you tug on it and the internal movements would feel so awkward they probably wouldn't struggle too much. Able to attach a leash to it (or can make it be a leash itself with a pump on the leash side)

I, myself enjoy swallowing things (in b4 gay jokes) and thought this up when a cable was hanging out my mouth...thought that it could be like a leash, how neat ^^

Be creative with it! if I could be credited with the idea I'd appreciate it on any pictures made using this.

Edit: someone suggested making the end on the mouth side have a ball gag built in. I like it :)