Normally, we just stop whatever it is that we're doing while waiting, and proceed to whatever it was we are going to be doing once we were both ready, because most of the time, we were both ready, we just thought the other person was not ready, and so we were waiting for them to be ready.

That being said, there are exceptions (where one person really isn't ready and is distracted as opposed to waiting), but even in the case of those exceptions, asking the question will generally also kick people out of a distracted mode as well.