Here is how I would do it.
Crap. Wrong forum. Mods, little help here?
I reported your post for you.
As for the question, I need to use both sides. On one side (probably the front) would be our very own:
On the back, this quote:
I’m a skeptic in Liberal’s favored definition, not a disbeliever.
Forgive quickly
Kiss slowly
In the words of the great Dr. Dre:
(spoilered for profanity)
You fucked with me, now it’s a must that I fuck with you. 
“Life is too short to wear sensible shoes”
VCNJ~
WhyNot, that is the most perfect t-shirt philosophy ever. Uncle Rojelio, that’s one of my favorite t-shirts too!
I’d be torn between two of my favorite quotes:
‘‘You will live or you will die. Both are good.’’ --Buddha
or
‘‘One must have chaos in oneself in order to give birth to a dancing star.’’ --Nietzsche
ETA: WhyNot’s t-shirt should be made into official SDMB merchandise.
If I could find an elegant way to phrase it:
“It’s not worth it to be easily insulted. If it is my friend, they didn’t mean it. If it’s not my friend, why do I care?”
Or, more likely…
These are my friends, I do not need to be afraid.
These are my friends, I do not need to be afraid.
These are my friends, I do not need to be afraid.
These are my friends, I do not need to be afraid.
…
I was looking for one about faith, hope and love, and I stumbled across this.
Is this a reference to something I don’t know about??
I can’t decide. Either “Don’t Worry, Be Happy!” or “Life ain’t nothing but bitches and money.”
Shit happens. Deal with it.
Pessimistic
Jesus loves you. Everyone else thinks you’re an asshole.
Optimistic
“There is not enough darkness in all the world to put out the light of even one small candle.”-Robert Alden
Yes, I think WhyNot’s could easily be the official slogan of the SDMB. And if they don’t take it, I’ll make my own CafePress shirt of it.
Mine is in my sig:
“Living well is the best revenge.”
“Carpe Diem”
Of course there are times that feel far more pessimistic, but there’s no need for a t-shirt for those times. I don’t leave my cave.
Sunspace, I prefer my med school professor’s version: “You can see a whole lot just by looking.”**
With apologies to Terry Pratchett: If you trust in yourself, believe in your dreams, follow your star - You will get the shit kicked out of you by people who worked hard and learned things and weren’t so lazy.
But my motto is: I may be lazy. But I am certainly not irresponsible.
Let me know if you do, 'cause I’ll buy one.
On the front:
Always look on the bright side of life…
On the back:
(All together now) do-do, do-do-do-do!
Mine would say:
“You are not awake.”
Save a tank, ride a Marine
What? I’m a 21 year old, I’m not exactly a complex creature at this point in life. 
Ok, but seriously, it would probably say something like, “Life is good” as I say that about 500 times a day. I’m the enternal (annoying) optimist.