When a hero makes a long monologue during the battle, and villain is staying quietly and listening. And vice versa.
(*) Wrong: Anyone who at least tried to study martial arts, know, that in the very moment when you'll distract yourself on anything during the (more or less) serious sparring, you'll get a punch in the face very quickly.
(*) UPD: Discussion below quickly revealed, that I was WRONG in starred paragraph. I made way too strong statement: 1) having in mind intuition, based only on specific experience of knife fights, which can't be generalized on everything; and 2) carried away by indignation
In truth, yes, there are IRL situations, in which fighters say phrases to each other during the fight - without "immediately getting a punch", as I wrongly wrote.
Now I would say the following instead:
"I don't believe that in real life fighters would make long (~5-10 minutes...) and consistent monologues in the heat of fight-to-death. I think that opponent would take advantage of it to attack battle philosopher. 
So when I see it in fiction, it breaks the immersion ✿ڿڰۣ— "


