CORBIN Bleu says he and his “High School Mu sical 2” co-stars expected the sequel would top the original blockbuster – but not like this.

“It’s one of those things that continues to shock and surprise everybody,” Bleu said yesterday, just days after Disney Channel’s “HSM2” shattered records by averaging 17.2 million viewers – the top-rated cablecast ever.

“It’s just cool to be a part of it, to be part of something that’s made so many waves and broken so many barriers,” he says.

“We all look at each other and say, ‘OK, now what? What’s going to be next from this craziness?’

“It’s very surreal,” he says. “I continue to be shocked and impressed.”

Bleu, who’s played Chad Danforth in both “HSM” movies, is in the midst of touring to support his new CD, “Another Side.”

He’d seen “HSM2” before it aired last Friday – he was on stage performing when it was actually on – but says he was bowled over when the numbers came in Saturday.

“I was sitting in the car and my publicist called and he said, ‘Are you sitting down?,'” he says. “My jaw dropped to the floor.

“My dad’s prediction [for ‘HSM2’] was 12 million [viewers] and everyone thought he was crazy,” he says. “This way surpassed what he thought.”

Bleu, 18, likens the pop-culture impact created by both “HSM” movies to being in the eye of a storm – calm in the middle, yet surrounded by mass tween hysteria.

“If you start to believe all the hype, that’s when people start getting big heads and become conceited,” he says.

“It’s better that we [in the cast] remain calm and let everyone else go crazy,” he says. “It’s so huge that if it goes to our heads it could be dangerous.

“We’re just actors who go in to do this wonderful job . . . but it wasn’t something we were losing our minds over like the rest of the world right now.”

Bleu says he’s in negotiations for the big-screen “HSM” movie, scheduled to go into production next winter.

“It’s definitely opened a lot of doors and propelled us to the next level of being household names,” he says.

“I was working a lot before – but there’s a difference between working a lot and being recognized for all your hard work.”