R.I.P. Batman dies

Not a bad innings got a good laugh out of him as mayor west on family guy

One of my favourite scenes:

Not as famous or important as the Hawaiian Pizza inventor, but RIP

Its sad I always loved the original batman .
But can someone please explain that surfing clip & why did they have to wear board shorts over there pants ?
Is it like kite surfers took that as the fashion statement ?
Is that were it comes from?