Vince Gironda had a different name for these … but they were named after a lifter by the name of Jim Bradford.
Take weight you normally use for overhead pressing and reduce by about 10-20 percent. Wider than shoulder width grip…let comfort be your guide. Start at normal clean position at collarbones, then drop just slightly before pressing. Press weight up till you just reach the top of the head, then move the weight over your head and lower behind your head till you contact the base of the neck. Then return to the front in the same way…it is a continuous back and forth movement. You should just clear the top of the head, so your arms never really exceed a 90 degree angle. Fight the tendency to “duck” the head to one side or the other to make the movement easier. One forward/back trip equals one rep. Mostly front and side deltoid, with some rear delt stabilization.