spontaneous - "Arising from ones own internal tendecny, dispositin,inclination, without external influence, consraint, compilsion; voluntary".

I don't know if there's some legal meaning of spontansous that is narrower than that; on the face of it none of those things Dave mentioned would in any way mean that the activities weren't spontaneous. For example, if, of your own free will, you travel half way round the world to take part in singing carols in a pub, that is a completely spontaneous action on your part.