A phrase indicating that one is about to do something stupid or dangerous. The image is that of a person at a party who asks a friend to hold their beer so that they can attempt some kind of ill-advised stunt. It is often used humorously to describe how something bad was followed by something even worse. A: "There's no way it's possible to jump from the roof into the pool. It's 20 feet away!" B: "Hold my beer, amateur." Wow that was a terrible game. It was like the one team saw the other team making dumb plays and was like, "Hold my beer."