It comes from the episode of Happy Days
Where Fonzie jumped over a tank of water with a shark in it.
( sp3ktor yes, he of the-onion-bag.com fame, Mon 7 Apr 2003, 10:49, archived)

yes, yes, yes
mists clear.
ta muchly
( Pootle where's his tart on his sleve?, Mon 7 Apr 2003, 10:53, archived)