If you say that someone is twiddling their thumbs, you mean that they do not have anything to do and are waiting for something to happen. While players openly questioned the umpire's decision, spectators in the ground had to twiddle their thumbs. ...

What does twiddling your thumb mean?

Be bored or idle, as in There I sat for three hours, twiddling my thumbs, while he made call after call. This expression alludes to the habit of idly turning one's thumbs about one another during a period of inactivity. [ Mid-1800s]

Where does the phrase twiddle your thumbs come from?

The figurative meaning of the term twiddle one's thumbs was first used in the mid-1800s. Previously, the phrase twirl one's thumbs had meant to wait idly or engage in a time-wasting activity. Related phrases are twiddles ones thumbs, twiddled one's thumbs, twiddling one's thumbs.