Boards
Songs performed live for the first ever time; and *you* were there.
I saw the first ever performance of Sorted For E's And Whizz by Pulp (as i'm sure a fair few others might have been on DIS) at Glastonbury 95. More recently but less excitingly; Lana Del Rey's Off To The Races at Manchester's Ruby Lounge.
Anyone else ever been present for a song's very first public airing?