OK -- sure I can remember The Star Spangled Banner (well most of the time) then there is the question of do you flow with the music or play THAT song straight forward?
But I digress --- actually I remember a couple people who come to mind who did flow with the music, had everything apparently committed to memory or were so adapt at their music craft that they could pick songs out of the air. --- the latter is a more accurate description. Mac Davis and Barry Manilow
Anyways Mac Davis appeared on tv -- with a comedy show probably in the mid to late 70's --- and would make up songs from the audience suggestions -- or play a song on the guitar and sing it also
Equally as talented -- Barry Manilow would appear on shows -- probably in the mid 80's and do similiar requests -- not from just his hundreds of songs he wrote -- but also audience requests --
that always fascinated me -- not that they could make up a song, or play one they had written, but also play and sing songs that were not their own.
Anyways -- sing and play an instrument -- always fascinates me!!!!!!!