Your spoken words don’t attract copyright until they are recorded in some material form. Your tweets may be too trivial and banal, but mine are definitely original. There is no copyright in the plot of a book or an idea for a game show format, play or film.
Most original creative work causes a copyright to come into existence. It can be an infringement to copy a small part of the work if it is considered substantial. This fact creates something of a fetter on an artist’s creativity as he must be certain that he is not being over inspired by another’s work. If you are accused of copyright infringement and do not believe you have copied, but have had provable access to the original work and there are substantial similarities between the original and your work, it can be extremely difficult to persuade a judge that no copying was involved.