Sylvester Stallone once packed a knife in his daughter’s schoolbag as part of a brutal self-defense strategy.

The Rocky actor, 77, has three daughters with wife Jennifer Flavin, 55, and gave the blade to their middle child, Sistine, after teaching his girls vicious life-saving fight tactics.

Sistine, now 25, said on the season two premiere of The Family Stone reality show: “He made us practice pepper spray each other. Oh my God, that’s so bad. He put a little knife in my backpack in fourth grade.”

The episode also saw Sly take Sistine and her sister Sophia, 27, to learn self-defense with the Defense Strategies Group.

He warned his girls, who both live in New York: “I’m not playing a game – these are the guys that have seen combat, faced death. This is the real deal.”

Two teachers, who were former Navy SEALS, then threw punches with the girls while wearing boxing gloves, but Sophia, 27 asked them: “When am I ever going to be doing this in New York?”

Sistine joked: “Every first date ever.”

She then almost got a date out of the self-defense class and revealed one of the trainers messaged her on Instagram.

Sistine said: “But I’m not his type and I’ll tell you why. He follows only girls that have really big curves.”

Sly later said on the reality show, which charts his family’s lives, he and Jennifer have permanently moving to Palm Beach, Fla., to be closer to their youngest daughter, Scarlet, 21, who is attending the University of Miami.

He told his other two daughters: “After long, hard consideration, your mother and I have decided, it's time to move on and leave the state of California permanently, and we’re going to go to Florida.

“I don’t want to shake things up, but I know my wife wants big adventure.”

He also said he “owes it” to Jennifer to go through this move as their home is now an “empty nest."

She added: “I need to change it up… being empty-nesters, we can get into a lot of trouble together.”

Along with his three daughters with Jennifer, The Expendables star Sly also has two sons with his first wife, 73-year-old Sasha Czack: Seargeoh, 44, and Sage, who died aged 36 from coronary artery disease in 2012.

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