cock

１４日未明、リオ市内で警官を装った複数の男がライアン・ロクテ選手ら４人の米競泳代表選手が乗ったタクシーを止め、彼らから金品を奪う事件があったのはご存知の通り。

Lochte: US swimmers are 'safe and unharmed' after robbery

"We got pulled over, in the taxi, and these guys came out with a badge, a police badge, no lights, no nothing just a police badge and they pulled us over," Lochte told NBC's "Today" show . "They pulled out their guns, they told the other swimmers to get down on the ground — they got down on the ground. I refused, I was like we didn't do anything wrong, so — I'm not getting down on the ground.

"And then the guy pulled out his gun, he cocked it, put it to my forehead and he said, 'Get down,' and I put my hands up, I was like 'whatever.' He took our money, he took my wallet — he left my cellphone, he left my credentials."

http://www.usatoday.com/story/sports/olympics/2016/08/14/ioc-report-of-ryan-lochte-robbed-untrue-reports-cite-mom/88717348/

詳細を伝えたUSA Todayのロクテ選手の生々しい証言を読むと、犯人のひとりが、"the guy pulled out his gun, he cocked it, put it to my forehead"とありました。"put it to my forehead"（「額に銃を突き付けられる」）前に"cocked it"されたわけです。

ここのcockedの意味は一連の行動から推測できると思います。cockには名詞、動詞ともにさまざまな意味がありますが（blogには決して書けないNao好みの意味もあり）、これは"to draw back the hammer of (a firearm) preparatory to firing"（thefreedictionary.com）です。つまり「〈銃の〉打ち金を起こす」ということで、勝利の美酒も一挙にふっとんだことでしょう。（UG）