In the same way it vital to ask the "smart questions", it is equally important to ask the dumb ones.
Whilst your milieu might be—say—comparing and contrasting the finer details of commission structures between bond brokers, if you aren't quite sure of the topic learn to be bold and confident enough to boldly ask: I'm sorry, but what actually is a bond?
Don't consider this to be an all-or-nothing affair. After all, you might have at least some idea about what a bond is. Rather, adjust your tolerance to also ask for clarification when you are merely slightly unsure or merely slightly uncertain about a concept, term or reference.
So why do this? Most obviously, you are learning something and expanding your knowledge about the world, but a clarification can avoid problems later if you were mistaken in your assumptions.
Not only that, asking "can you explain that?" or admitting "I don't follow…" is not only being honest with yourself, the vulnerability you show when admitting one's ignorance opens yourself to others leading to closer friendships and working relationships.
We clearly have a tendency to want to come across as knowledgable or―perhaps more honestly―we don't want to appear dumb or uninformed as it will bruise our ego. But the precise opposite is true: nodding and muddling your way through conversations you only partly understand is unlikely to cultivate true feelings of self-respect and a healthy self-esteem.
Since adopting this approach I have found I've rarely derailed the conversation. In fact, speaking up not only encourages and flatters others that you care about their subject, it has invariably lead to related matters which are not only more inclusive but actually novel and interesting to all present.
So push through the voice in your head and be that elephant in the room. After all, you might not the only person thinking it. If it helps, try reframing it to yourself as helping others…
You'll be finding it effortless soon enough. Indeed, asking the dumb question is actually a positive feedback loop where each question you pose helps you make others in the future. Excellence is not an act, but a habit.