For most of my childhood and teen years, I preformed with a boy choir that took an annual tour somewhere around the world, most of the time it being international. I could probably write a book filled with funny stories about things that happened during the trips. Here's one of the many:
In this boy choir, we have sung a large variety of songs, everything from Bach to the Beetles. One year, we were dong a collection of songs from around the world, and one of those songs was a Aborigine song. The song was played with a large drum with a deep bass sound, and only had one word: "Tabu", meaning holy. It was a quite frightening song when done correctly. I was the lucky soul who got to beat on the darn thing. I was 15 at the time, and had already had plenty of experience with percussion in my school marching band, so I was the appropriate one to play it.
Well, that year, we took our annual concert tour to China, and the drum was too big to bring with us. We still planned to preform the piece, even though we didn't have the drum, hoping that when we did preform it, we would be able to find a drum that someone could let us borrow.
Our first concert happened to be on international children's day. So with a little advertising help from the Chinese government (which we somehow had very strong connections with), our concert was jam packed with over 2,000 people.
It was intermission, and until then our director wasn't able to find a drum for us to use for the Aborigine song. However, during intermission, he came up to me with a empty water jug, one of the things that you get water out of at an office. He wacked it with his hand and said "How's this?". I thought he was kidding, but he wasn't. It actually made a very deep bass sound, one that was what the song needed. So we decided to use it.
I swear, the audience was in fidgets whispering to one another wondering what the heck I was doing with an empty water jug as the choir went on after intermission. The song was first. It actually went quite well, despite me playing with something that had never been used as a legit instrument before. The jug was able to fill up the entire concert hall. As long as I wacked it hard enough. I had just invented a new instrument.
We gave numerous concerts and in about all of them we were somehow able to find an empty water jug at the last second and use it in the concert. One of these concerts was even televised nationally throughout China. So I played a brand new instrument in a semi-professional concert setting that no one had never really played before, on national television. Talk about improvising!