Or
B) Get impatient, cut them off and tell them everything you know about the topic?
Or
C) Patiently let them finish, THEN tell them you already know, and everything you know about the topic?
I personally have a tendency to be an impatient douche sometimes so I admit I don’t always handle these situations with the greatest patience & social grace.


Somewhere between B and C. If I know more about a subject, I can usually tell pretty quickly. I’ll try to engage early on with a “yes and” kind of response that completes their latest point and demonstrates knowledge of what they were going to go on to say. I’ll try not to be condescending, and present my thoughts as enthusiastic dialogue.