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1.
A convo blocker plays on the gaming term Combo Blocker. This is when someone performs an action or move that stops another player from successfully performing a combo. In that sense, a convo blocker is when someone, either in a large group, or one-on-one, says something that completely halts the flow of a conversation, usually to a dead silence for at least one minute, during which people share awkward glances and shifty stares.
Greg: So what do you think about our final exams coming up?

Nick: Well, I've contemplated suicide in the last few days.

Greg: (Silence, awkward stares etc.) (A few minutes later) Dude, that was a total convo blocker.
by Vladimir Czekov Raskolnikov April 30, 2010