I came across this article regarding skateboarding slang and thought it was pretty funny so I thought I would publish there idea of what the commonly most used phrases where.

Sick – this means the same as “cool” or for you older guys, “rad”. Pretty much anything can be sick. You can pull off a sick trick, have a sick board, or a skatepark can be sick. It’s one of those slang words like “bad” was a decade ago, meaning the opposite. Along with “sick”, something really cool might get called “ill”, “insane”, “gnar” (short for “gnarly”), or even “rad” or “righteous”.
Stoked – to like something or to be excited. I am stoked that you are reading this. I’m stoked I can land a tre-flip. The word comes from making a fire bigger – when you add fire to it, or fan the flames, you are “stoking” the fire.
Sketchy – not well done, or not trustworthy. A sketchy trick looked badly done (“clean” is the opposite – a clean trick looked flawless). A sketchy person is someone who you don’t want to bring home for dinner. A sketchy skateboard is a piece of junk that might break. I think it’s funny that the shoe company “Sketchers” tries to make shoes that LOOK like skate shoes, but are, in fact, sketchy.
Bail – to bail is to either fall, or to jump off of your board right before falling. It doesn’t get used all the time though – some people just say to fall or crash. The word “bail” is more traditional in skateboarding, but if the people you are around don’t use it, you might sound like you’re trying to hard if you insist on saying “bail” all the time!
Poser - this is someone who looks like a skater, or who claims to be one, but who doesn’t know anything about skating. This term can be pretty hurtful, so don’t use it lightly. And it’s tough to know if someone truly IS a poser – read Posers Vs Slow Learners for more.