What works sometimes is to raise your hand slightly and then: A) as politely but forcefully as possible admit you don't care what they are talking about ("I am

What works sometimes is to raise your hand slightly and then: A) as politely but forcefully as possible admit you don't care what they are talking about ("I am afraid you have lost me here") then either pivot the conversation or make an excuse to leave or B) repeat to them in brief what they have said and affirm that you are completely with them on their point and either add your point to it or pivot the conversation or make an excuse to leave