While teabagging someone (putting your testicles over their eyes) you then shine a flashlight over your testicles giving your victim and IMAX-esque view of your testes and testicular veins. Made popular by eager high school students trying to find the vas deferens.
Also a cure for stuttering emo kids.
Matt and Dave walked in on Tom giving Chrissy a testicular eclipse. Shock therapy ensued.
Emo Danielle was given a testicular eclipse by peepants to cure her stuttering. Noone understands her angst.