Today my brother and I decided to set Alan A'Dale to Fergie's song Glamorous. We did this by bringing up two videos on YouTube, one featuring the song and the other one being the actual video of Alan A'Dale, and muting the latter video so that all we could hear was the song from the first one. It turns out they fit frighteningly well together, with the lads singing in Alan A'Dale coming in at just the right times to perform Glamorous somewhat convincingly.
For reference, Alan A'Dale is a song originally performed by Peter Cook, Dudley Moore and three other gentlemen on Not Only...But Also. You can view a staging of this wonderful piece of music
here. This is the video my brother and I used (in fact, I'm pretty sure it's the only video of Alan A'Dale on the internet at the moment). Try setting it to Glamorous yourself, but be sure to start them at the same time to get it just right! (Wait until Dud does his solo bit and mouths Fergie's words almost perfectly.)
This reminds me of when there used to be a video of Step in Time perfectly synched to Michael Jackson's Beat It floating around on YouTube. It has since disappeared due to copyright issues, but it was brilliant and made me want to make Dustin learn how to moonwalk. If only it would resurface someday...