The meaning of a kook according to the Urban Dictonary:

‘1. someone posing very hard as a surfer or skateboarder.

2. someone that goes to every surfing or skateboarding event to hangout, compile pictures, start conversations, and generally be seen with real surfers or skateboarders. ‘

Our favorites in the video:
“Going straight is under-appreciated.”
“It’s all about the spray.”