The actor was trying to get into character as Steve Jobs for 2013 movie "Jobs" and decided to take on the late tech icon's eating habits to get a feel for the man - but he went too far.
"He really gets into his roles...," Gad explained. "To get into the role of Steve Jobs he did Steve's diet, so he did this fruitarian diet thing... and he got really sick doing that."
"Ash and I started dating and I had to take him to the hospital because he was on a grape diet," Mila added. "Guys, don't go on a grape diet... He had pancreatitis or something."
But while Josh and Mila didn't agree with the lengths Kutcher took to get into character as "Jobs", they both insisted he's a great guy - and a really good actor.
"I love him," Gad said, while Kunis added, "He's a much better actor than me."