I am often both requesting and receiving verbal problems related to the software I maintain (an Engineering simulation and analysis tool). When receiving a problem verbally is to slow the other person down by challenging any assumptions they may be making. By asking them to clarify it allows me to build a mental model of the problem before at a sustainable pace and also helps them identify a bad assumption they may be making.

When I am asking someone else to be the rubber duck I strive to highlight any assumptions I am making at each step of defining the problem. If I don't do this the other person will usually struggle to keep up.