You never know what’s going to happen when musicians get together in the recording studio. Sometimes the most unlikely collaborators end up making sweet music together, while surefire pairings end up falling flat. Snakkle takes a look at some of the most interesting, entertaining, and just plain unfortunate musical mashups in recent pop history.

What is heavy metal? For some people, that topic that can generate more controversy than religion or Tim Tebow. Over the years, metal has split into more genres and subgenres than we have room to list here. Bottom line: We say you know heavy metal when you hear it. So there. Now that that’s settled, let’s take a look at some of the heaviest rockers around before they were stars.