A blanket party (also known as "locksocking") is a form of corporal punishment, hazing or retaliation conducted within a peer group, most frequently within the military or military academies.
The victim (usually asleep in bed) is restrained by having a blanket flung over them and held down.
Other members of the group strike the victim repeatedly with improvised flails, most often a sock or bath towel containing something solid, such as a bar of soap or a padlock.
[1] In 2015, a United States Army veteran was diagnosed with PTSD (post-traumatic stress disorder) after being the victim of a blanket party during basic training in the late 1970s.
[2] The term "blanket party" was popularized by the Stanley Kubrick film Full Metal Jacket.