MASON, Ohio — A Seymour, Indiana woman unknowingly helped an Ohio amusement park celebrate a major milestone Wednesday.

“Really?!” Grace Timmons could be heard asking excitedly after being told she was the 20 millionth rider of the Diamondback coaster at Kings Island.

The 23-year-old became the lucky rider at 7:01 p.m. during a visit to the park with friends.

Timmons received an assortment of Diamondback-themed gifts to commemorate her historic ride.

The Diamondback opened in 2009 and stands 230 feet at its highest point with a drop of 215 feet at a 74-degree angle. It’s made up of 5,282 feet of steel track and reaches speeds of up to 80 mph.

According to Kings Island, Diamondback has an “open-air, stadium-style seating which offers riders an unobstructed view no matter where they may be seated on the train.”

Timmons couldn’t quite believe she was the 20 millionth rider at first.

“I for sure thought I was getting pranked,” she laughed. “I for sure was looking for cameras because I thought I was getting pranked.”