How much does childbirth hurt? And can men possibly experience an equivalent? Dr Beth Darnall, a pain psychologist at Stanford University, in the US, told Men's Health magazine earlier this year: "How we experience pain is very personal and very relative. One person's kidney stones pain could be as severe as another's childbirth . [But] I don't think there's an exact equivalent [for men] to pushing a human being out of your vagina."But that has not stopped a few men from attempting to find out exactly how childbirth feels.Last year, a hospital in Shandong, China, gave about 100 men the opportunity to experience childbirth pain by hooking them up to electrical currents."It felt like my heart and lungs were being ripped apart," said Song Siling, one of the test subjects.And now US broadcaster and YouTube star Penn Holderness has become the latest male guinea pig to find out just how much childbirth hurts.As a Mother's Day gift to his wife, Kim Dean (by whom Holderness has had two children), he volunteered to be attached to a "labour simulator" for several minutes.In the video, which has been viewed over 1.7million times, Holderness was connected to a device that made his recti, muscles at the front of the abdominal wall, contract in much the same way as a uterus during labour.He is seen writhing and screaming, even when the pain threshold is set to only 40%.''It feels like someone is trying to push something out of my stomach through my anus,'' said Holderness.He begins punching the pillow at pain level 6...