User blog comment:Crazy sam10/Xbox Community Update - 22 August 2013/@comment-90.220.30.192-20130822105558/@comment-12293947-20130822194750

IIRC, Jumping Jacks was first coined by Telixion from Machinima when he went to Treyarch and hunted for the Die Rise Easter Egg. They asked him what he wanted to call them and they would use it, and he said Jumping Jacks.