This is a very rare phenomenon, when you kill someone with the Righteous Bison, the enemy would A-pose.
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https://www.youtube.com/watch?v=t0_GQtVYOLM
Valve added statues of Soldier on all official servers as a tribute to Rick May, voice of the Soldier.
And in Main Menu, it shows only Soldier and new soundtrack will play.
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https://www.youtube.com/watch?v=PtkTrA-MFkc