Here's an incomplete list of exactly WHAT this shirt means:

Going around clockwise, starting at the top

WTF, OMG, LOL, ASL, : ), ^_^;; - Random internet acronyms

Goatse - You have to see this for yourself (NOT SAFE FOR WORK OR PARENTS, VERY DIRTY) http://www.putalocura.com/autocontenido/links/F120/goatse.jpg

L337, Pwned - Leet speak
http://www.urbandictionary.com/define.php?term=l337&r=f
http://www.urbandictionary.com/define.php?term=pwned&r=f

Space Invaders - classic arcade game
http://radio.weblogs.com/0113064/images/2003/08/09/invaders.gif

All your base are belong to us - old internet hype
http://www.planettribes.com/allyourbase/story.shtml

A winner is you - another old internet hype
http://www.urbandictionary.com/define.php?term=a+winner+is+you

Bigger wang - a play on the barrage of spam mail flaunting one's ability to get a "bigger wang" with certain products

John Titor - No clue. It seems like this guy thinks he's a time traveler.
http://www.johntitor.com/

Snake, badgers, and mushrooms - funny flash animation.
http://www.badgerbadgerbadger.com/

Winner! Winner! Winner! - A play on pop up ads that taunt you to click on them by telling you that you are a winner.

I love DSL - absolutely no clue.

The bathtub - Tubgirl, a follow up to goatse. (NOT SAFE FOR WORK OR PARENTS, VERY DIRTY)
http://illegalthoughts.com/tubgirl.jpg

RoflCopter - http://members.cox.net/pimpbot9000/roflcopter.gif

Fap - the sound of masturbation, coupled with (safe for work) http://www.mlcsmith.com/humor/art/god-kills-kitten.jpg