In this quote, P.G. Wodehouse expresses concern about what someone named Tom will say when he begins speaking. This implies that Tom may have a tendency to either speak his mind freely or potentially say something unexpected that could cause discomfort or tension in a situation. Wodehouse's use of worry indicates a level of uncertainty regarding Tom's upcoming comments.

The essence of the statement reflects a common human experience: the anxiety that arises when anticipating someone else's words, particularly if that person is known for being candid or unpredictable. It emphasizes the unpredictable nature of communication and the potential for awkward moments during interactions.