ET has more with MARIAH CAREY and NICK CANNON at Six Flags Magic Mountain, and only our KEVIN FRAZIER is with the newlyweds at the ultra exclusive, super-sized surprise from Nick to his new bride!

"I'm not big on surprises, but this is a smash hit!" Mariah exclaims.

Just 100 friends and family were allowed inside, where the park was transformed with pink and purple roses, personalized cupcakes, ring pops, balloons and of course -- butterflies.

Tune in to watch our exclusive coverage tonight, as Kevin hits a roller coaster with the hot new couple!