A guy from my group of friends lacks a sense of opportunity, he can't take clues if someone is disinterested in the conversation or tries to make the effort to get someone interested, he just bombards people with random stuff whether they like it or not. He often talks about obscure tv show references nobody in the group have a clue, he starts the conversation without knowing where it's going and makes lots of detours, without any conclusion: he just talks and talks.
Sometimes he's calmer, other times he's on fire. Today he was on fire and went on a monologue for a long long time, leaving little space for me to talk. His closest friend just tells him to shut up, often very rudely, and I don't like to see that but I understand why. I tried everything: Asking him nicely tothat I wanted to listen to other people, asking him less nicely, taking the lead of the conversation to get him to talk something I was interested, or getting him to finish what he started. All my attempts failed and he just plowed through the conversation with whatever he felt like talking.