It feels like you are being flushed down a toilet. Royal Flush Extreme is Bowl Water Slide ride at Wet n Wild Las Vegas water park.

"The ultimate Las Vegas attraction: Royal Flush Extreme is a fan favorite. This unbeatable slide isn't for the faint of heart. The adrenaline-pumping ride on this massive bowl slide will get riders pulses racing." - Wet n Wild Las Vegas website

"Riders plummet through the enclosed tube slide then fight the centrifugal forces of the Royal Flush Extreme which pulls riders around and around before abruptly releasing into the exit tube for splash down!" - Wet n Wild Las Vegas website

Another similar ride you can find in SoCal is the Dragon's Den water slide at Raging Waters in San Dimas.