Article continues below advertisementKevin Hart didn't hold back as he took aim at Nick Cannon's unusually high fertility. The comedian, 46, did a rapid-fire roast during an appearance on the "Call Her Daddy" podcast on Wednesday, April 29, and let it rip when the topic turned to the father-of-12.Article continues below advertisementSource: @KillaKreww/X; Call Her Daddy/YouTubeKevin Hart called Nick Cannon a 'sperm diffuser' in a rapid-fire roast.