Coins will fall from the sky. Some of them are real, and some of them are fake. The fake ones will either deal 50 damage or instantly kill you with an explosion if they are touched.
"Counterfeit coins start falling from the sky! They’re not collectable, and they may harm you. The fake coins stay even after the round is over, and will disappear after 100 seconds. To tell which coins are fake, the letters on the coins are swapped. Normally it would display "SD". It’s hard to tell at a quick glance so make sure you know for sure before collecting them."