twiddling your thumbs

Twiddling your thumbs, or to twiddle your thumbs, means to be doing an action which is not at all useful to the current situation but that you do as a way to pass the time. Twiddling your thumbs literally can be to pass the time or simply as something to keep your hands busy while you anxiously wait for something to happen. However sometimes the phrase is not literal, but a way to say someone is biding their time until something occurs.