Actor Brad Pitt has spoken out about the red carpet attack that left Ukrainian TV presenter Vitalii Sediuk behind bars.
The notorious prankster accosted Pitt at the world premiere of Maleficent in Hollywood last week.
"I looked down and the nutter was trying to bury his face in my crotch," Pitt told People magazine.
He said Sediuk would make life difficult for genuine fans hoping to get autographs from the stars.
Sediuk, 25, who is known for pulling pranks on celebrities, spent two days in jail after being pulled off the red carpet by security guards.
He pleaded no contest to battery and unlawful activity, and was sentenced to three years of probation and a year's worth of psychiatric counselling.
The TV presenter was also ordered to stay 500 yards (457m) away from all celebrity events, including awards shows and premieres. He must also stay away from Pitt and his fiancee Angelina Jolie, who stars in Maleficent.
In his statement about the incident, Pitt said: "I was at the end of the line signing autographs, when out the corner of my eye I saw someone stage-diving over the barrier at me.
"I took a step back; this guy had latched onto my lapels. I looked down and the nutter was trying to bury his face in my crotch, so I cracked him twice in the back of the head - not too hard - but enough to get his attention, because he did let go.
"I think he was then just grabbing for a hand hold because the guys were on him, and he reached up and caught my glasses."
"I don't mind an exhibitionist, but if this guy keeps it up he's going to spoil it for the fans who have waited up all night for an autograph or a selfie, because it will make people more wary to approach a crowd."
Referencing one of Sediuk's earlier red carpet attacks, where he put his head underneath actress America Ferrera's dress, Pitt added: "If he tries to look up a woman's dress again, he's going to get stomped".