You’re drinking a can of Guinness. As you near the bottom, something rattles around inside the can. You look inside and see, to your surprise, what looks like a ping pong ball. Was it a factory error?

Add Yahoo as a preferred source to see more of our stories on Google. Why there's a white plastic ball in Guinness beer cans The Guinness widget is a tiny, plastic ball inside beer cans. During ...

Guinness lovers can now snap up the Nitrosurge gadget at its cheapest price since Black Friday and recreate the perfect pint ...