A good word that has two slightly different meanings. In the UK it is what street musicians do but it can also mean when you wing it. I recently heard about what an amazing performance Richie Havens did at Woodstock. What happened as he was finishing his usual set was that he got told to "carry on". The roads were blocked and no other artists could get in. Richie then went on to do a 4 1/2 hour impromptu set. (Where was Springsteen when you need him lol).
My question is what is the longest you have performed for in one stretch. Mine was busking on Xmas eve for 5 1/2 hours. I had a family to buy for and it meant singing the same 5 Xmas songs over and over again. All without a mic.