Sylvester Stallone can't help but intimidate his daughters' boyfriends.

The 'Rambo' action hero - who has Sophia, 22, Sistine, 20, and Scarlet, 17, with wife Jennifer Flavin - admitted while he is totally outnumbered at home, he has gone into a 'macho mode' when meeting his children's suitors for the first time.

He told the Daily Express newspaper: ''I do a thing called the Crushing The Hand Test. I work my hands very much, and they're very strong, so when I meet her date I really clamp down - and they're not ready for it.

''I see their faces changing colour, because they wanna be Alpha dog, and I know they'll never forget it. It's not intentional, but when you have a daughter, it's a form of temporary insanity.

''When some guy walks in the house, you're not yourself anymore... ''My daughters are like, 'What are you doing?' But I just can't help it.''

The 72-year-old blockbuster star also revealed he has tried to discourage his girls from following in his footsteps and starting their own acting careers.

He explained: ''I said, if you really want to be an actress, it's an incredibly difficult decision. You can't do it half-way. You're all in, and your heart is going to get broken many, many times...

'''We don't like you. You're not good enough.You're a failure' - I've heard this. I say: You better be ready to have your soul torn apart. And then you've got to glue it back together and keep going on - and still there's no guarantee.

''So if you're going to be an actor, be prepared to go through hell, really hell. So, on that note, I say: How about you learn to ride a horse? Enjoy your life!

''They're thinking about it now. ''But I don't recommend it, unless it's something you can't control, and you breathe it.''