Frickin'
Adjective used to modify a Noun.

Friggin'
What one says when he gets snaked.

Front Porchin' It
Cruising down the line in the waves vortex just under the pitching lip.

Frontside
Facing the wave while surfing. A goofyfoot going left or a regularfoot going right. Also called forehand.

Frost
Fine, hot, sexy, cute.

Frosted
When a surfer cuts hard and sprays someone paddling back out to the lineup.

Frothing 
Used to say you're stoked.

Fudge Tunnel
A tube at a break where the water's very yellow or brown. Can be anywhere in the world where there is water pollution. The San Diego region has several breaks that have the fudge tunnel effect.

Fujiwara Effect
When two tropical cyclones rotate about each other. This is caused by the lack of steering winds in the upper atmosphere so the cyclones actually end up affecting each other.

Full On
Going for it; all Out. Having a really good session.

Fullsuit
As the name implies, a wetsuit that covers the whole body. (Though some companies make short-arm fullsuits) Ranges in thickness from 2mm to 6mm, but the most common fullsuits are 3/2mm and 4/3mm. (Called "steamer" in Australia.)

Fully Developed Sea
A sea state whereby all potential wind (wave producing) energy has been transferred into the water.

Fully Sick
When your mate is rippin' and asks you how he went? Now is the time to say..."fully sick, mate!"

Funboard
A compromise surfboard design, combining the superior paddling attributes of a longboard, but stripped of some of the unwieldy length and bulk so the rider may have a taste of shortboard maneuverability.