It's actual gameplay footage from Army of Two: The 40th Day, containing tons of gunfire, explosions, and the worst zoo ever.

The Army of Two franchise is essentially the story of two pals who get mixed up in all sorts of whacky military hijinks. It's a buddy film, and what would a buddy film be without the odd amazingly quotable catchphrase. I believe "Worst. Zoo. Ever." fits the bill quite nicely.