A locking device having a cylindrical plunger and a cylindrical sleeve for releasably and rotatably receiving the plunger, the sleeve having an open top portion, and a bottom portion. A keyway is provided axially disposed along the length of one of the plunger or sleeve, and a lip circumferentially disposed around the same plunger or sleeve. A key is also provided on the other of the plunger or sleeve, the key slidably mating with the keyway. A spring member is disposed within the sleeve and is compressed when the plunger is inserted into the sleeve biasing the plunger out of the sleeve. To lock the device the plunger is inserted into the sleeve, the key sliding along the keyway through the lip, the plunger compressing the spring member, and then the sleeve and plunger are rotated with respect to each other and released, the spring biasing the plunger out of the sleeve and locking the key onto a surface of the lip. To unlock the device the sleeve and plunger are pressed together, the plunger compressing the spring member, and rotated with respect to each other until the key and keyway are aligned with each other, the spring biasing the plunger out of the sleeve. The plunger is then removed from the sleeve, the key sliding along the keyway through the lip.