This week's poll question will push your rock music knowledge to the extreme:
What is the best rock collaboration of all time?
We're using the 'rock' label loosely here; it can be any guitar-based collaboration from the rock world, whether that crosses from rock to metal to pop and beyond. Obviously you'll want some kind of guitar connections to appeal to other UG voters.
To help stir your idea pots, there's plenty of angles you can take beyond simple collaborations like David Bowie and Mick Jagger's ill-fated "Dancing in the Street." You might think back to the time Dave Grohl recorded drums for Queens of the Stone Age on their "Songs for the Deaf" album, or when Rick Rubin revived Johnny Cash's career by working closely to redefine his music.
If you've come up with a particularly unusual collaboration, try to express why it's so important to help sell yourself to other UG readers. You can only make it to the top 10 if you win the votes!
Post one nomination per comment, and upvote any you agree with. And yes, we welcome comedy entries, but they'll probably be segregated from the main top 10 when we post it on Friday. Good luck!