I assume there's a legitimate use for these things at sperm banks or fertility clinics. Seems a bit overengineered compared to just nutting in a cup, but I guess it avoids the possibility of missing. More importantly, it could be useful for someone with mobility issues who can't easily stimulate themselves.

("sperm banks" got auto-corrected to "supermarkets" at first...now there's an image)

edit: oh, you were asking why it went viral, whoops