Yeah, the Guinness pint is now 14.9 fucking ounces in the US. Relatives of mine in Ireland confirmed that if they did that shit there, they'd have another rebellion.
It's a plastic ball with a tiny hole in it. When you open the beer, the compressed gas, nitrogen and co2, sprays out of that hole into the beer, making it creamy and frothy. Guinness isn't meant to be carbonated like most beer, so it's never "foamy"