Airhead- An intellectual lightweight
Awesome - Very good (e.g. "That movie was totally awesome!")
Audi - Out of here (e.g. I'm audi.) Often confused with Outtie, this misunderstanding then went into widespread use.
Barf - To vomit
Baldwin - Handsome boy or man (from the Baldwin brothers)
Barf bag - Jerk
Barney- An unattractive boy or man (presumably from The Flintstones character Barney Rubble)
In other contexts, the term "Barney" is used to refer to police officers; in that case, it derives from Barney Fife.
Betty -Beautiful girl or woman (stated on the Whatever! DVD edition that the term 'betty' comes from The Flintstones character Betty Rubble)
Bitchin' -Cool (aesthetic)
Bro Brother, meaning friend or dude
Buggin' - Freaking out (usu. mildly)
Bum -Another word for "to borrow" (e.g. "Can I bum a cigarette?")
Dork - Originally slang for a penis (as used in Sixteen Candles), but eventually came to mean geek or nerd or a clumsy or eccentric person.
Dude - General term for a male, but may also be used in a derogatory manner, or to get someone's attention
Dweeb - Nerd and Loser
Classic - Great
Fiesta - Party
Fer sure! - Certainly
For seriousness - Absolute Certainty
Gag me with a spoon! That's disgusting (from a method of inducing vomiting)
Gnarly - Good, Great
Grody - Disgusting (e.g. grody to the max) (from "grotesque")
Gross - Disgusting
Hella - Lots, Many, Excessive, Very (That was hella cool. I haven't done that in hella days)
I'm like... - (When talking about yourself) emphasis placed on the "li" in "like."
I'm so sure! - (spoken sarcastically) I don't believe you.
Joanie - Unhip girl (from the Joanie Cunningham character on Happy Days)
Later! - Goodbye!
Later days! or Later dates! - Goodbye! (Usually said by Tino at the end of each episode of Disney's The Weekenders)
Loadie - Stoned boy or girl
Monet - Someone (or thing) that looks good from afar, but up close it's a total mess. (e.g., "That hag is a full-on Monet!")
Postal - To go insane/freak out/bug (as in "going postal".)
Psych! - Just kidding
Rad - Very cool (from "radical")
Rays - Sunlight. (e.g., "I'm going to the beach to catch some rays.") See UVs.
[I know] Right?/Right on Used as bland filler when there is lack of interest or content for a response or to express agreement with indifference or cockiness. (e.g. That bikini looks so hot on you Heather! Right.!?; Hey bro I found 20 bucks under the seat of my car! Right on!)
Scarf - To eat, usually very quickly (e.g., "I totally scarfed that burger!")
Sketchy - Weird/suspicious (e.g., "that guy looks sketchy"; "I dunno, you were acting kind of sketchy about [x]."
Spaz -A hyperactive nerd/geek/klutz/a confused person. (e.g., "That guy is a total spaz!")
Sweet! - Used to express excitement, satisfaction, camaraderie, happiness for another person/thing/event. (e.g., Dude I like totally dicked a Betty today! Sweet!) Strong emphasis and elongation of the Es Sweet.
To the max - More of the preceding adjective (e.g. grody to the max). "Max" being short for maximum.
Tripendicular - Awesome; literally “a triangle with three perpendicular sides”, a geometric impossibility in Euclidian/plane geometry (it is possible in spherical geometry), therefore synonymous with "unbelievable”; the stressing of the first syllable is by association with “trip”, referring to the experience felt while under the effects of illicit drugs.
Tubular - Very cool
UVs - Ultraviolet radiation, the property in natural sunlight that causes skin to tan. (e.g. I'm heading down to the beach to get some UVs.)
to Veg (out) - To rest (from "vegetate")
Way - Used as an adverb for emphasis. (e.g. "That was way cool"); also meaning "yes" (e.g. in response to the exlamation of disbelief "No way!", the response "Way!")