Just wondering if it's going to be that they have to sing:

a) A Queen AND a Gaga song

b) A Queen OR a Gaga song
( I like both artists but that'd be a bit of a cop-out as themes go )

c) Mash-ups of Queen/Gaga ( this kind of thing )

http://www.youtube.com/watch?v=kUEYO2tgFIE


Although I'm guessing they will probably get to choose, so it might be that some will do a Queen song , some a Gaga and maybe one person such as Misha will do a mash-up.
Then I'm guessing Brian May will appear on Sunday to perform with Gaga - that would make sense of this theme.