mic drop

"Mic" is an informal shortening of "microphone."

1. verb To dramatically drop one's microphone (or, especially, to mimic the motion of such) after a particularly decisive or impressive performance, action, or statement. Did you see him mic drop after that rap battle? Right in the middle of the meeting, she exposed her boss's crooked dealings, announced that she was quitting, mic dropped, and walked out of the board room.

2. noun A decisive or impressive statement or action. You were so confident during your presentation that the last slide was like, boom, mic drop! I think the partners were very impressed. That dunk was the mic drop that ended the series.