If I were about to kill a bunch of vampires via a cunningly contrived trick involving artificial sunlight
I would want playing in the background either "Blinded by the Light" by Manfred Mann, or "Always the Sun" by the Stranglers.

What extremely unlikely events have you already chosen the music for?

Alternatively, what extremely unlikely events would be ironically themed by your favourite song?
( The Light in Chains don't touch the Pope's boner, Wed 28 Apr 2010, 23:48, 3 replies, latest was 16 years ago)

I would use Hendrix's 'Voodoo Chile'
as the soundtrack to a trip to Chile.
( Monty Boyce, My cheese game is strong, Thu 29 Apr 2010, 9:16, Reply)

Following that
I'd have Led Zeppelin's 'Going To California' as the soundtrack to me going to California.

I'm FUCKING GOOD AT THIS, me.
( Monty Boyce, My cheese game is strong, Thu 29 Apr 2010, 9:29, Reply)

If I were to get a job of promoting rock bands in California it would be great!
I'd probably have to do some on-job training, and I would listen to the Under Assistant West Coast Promotion Man all day.
( Larry Vest One day at a time, sweet Jesus, FFS., Thu 29 Apr 2010, 9:19, Reply)