Sylvester Stallone avoids social media because it gets him into "trouble."

The legendary actor found himself in hot water last year for criticizing fellow Hollywood star Bruce Willis on Twitter - after Bruce dropped out of his movie The Expendables 3 over a pay dispute - and he now chooses to be very "careful" about using social networking websites.

"Every time I use social media I get really in trouble! I think George Clooney said it best when he said you've got to be an idiot to be celebrity and use Twitter. You wake up in the morning when you're sober and your career is over! You've got to be really, really careful. You think you're a genius up there in the middle of the night and you wake up an idiot," he explained.

The 67-year-old star admits he isn't technologically savvy and doesn't quite understand the purpose of photo sharing mobile app, Instagram. "Everyone keeps wanting me to get on Instagram. Is that for younger people, Instagram? For, like, pervs? 'Here we are at the hospital getting our back checked' or 'I'm on dialysis... here we are!' I'm really basic with the iPhone. I think I've figured out how the camera works and that's about it. I keep it very simple," he quipped.

Sylvester - who is best known for his legendary role as boxer Rocky Balboa - once again finds himself in a boxing ring in his movie Grudge Match, which co-stars Robert De Niro, and he reveals he was inspired to get into the sport after being bullied as a child.

Speaking to BANG Showbiz at the Grudge Match press conference in London today, he said, "I was at school and there was this big bully and he was coming after me, so I just started moving around and started to pepper him [with punches]. And I was like, 'Wow, I like this.' Then I became the school bully till someone bigger came along and beat me up."

The actor also admits to being something of a wild child as he was expelled from no less than 14 schools, which he claims is due to having attention deficit hyperactivity disorder (ADHD). "You can probably tell right now I tend to be a little hyper, and that's exactly what it is. Back then they had no tolerance for it. If you're out there flirting with some girl, walking outside, watching a caterpillar walk up your arm... Things like that you were more interested in than school, you were gone. Especially in the days of the Catholic schools. Finally they just said, 'You cannot come back to school, period' and I was like, OK, I'll become an actor. Today they call it ADD, but I was ADDAA+AA!" Sylvester recalled.

(FYI - You can also follow VIP Breakdown on Twitter.)