Sorority Row (2009) on Netflix

During a party in the Theta-Pi sorority house, the sister Megan plays a prank with her unstable boyfriend Garrett simulating an OD after using pills. Her sisters Jessica, Claire, Ellie, Cassidy and Garrett's sister Chugs suggest to dump her "body" in a lake and the stressed Garrett sticks the tire iron through the Megan's chest killing her. Cassidy decides to call the police, but the sisters are convinced to dispose the body in a shaft and keep in secret under the leadership of Jessica that blackmails Cassidy. Eight months later, in their graduation party, the sisters receive a creepy message with the picture of the tire iron in the beginning of a nightmarish night.