You woke up as the opposite gender?
Go back to sleep?
Breathe a sigh of relief.
Try to understand man’s fascination with his penis! 
Celebrate the fact I no longer have to suffer from the pain of “that time of the month”
Go spend some of that extra money I’ll be earning!!
Try out that ping pong ball trick.
Celebrate the fact that I can now marry a man legally. Though with my luck, I’ll still be gay, and now attracted to women.
The first thing that comes to mind is that I’d become really pissed at all the hassle it would cause.
I know nothing about tampons, or makeup, or any of that kind of thing.
Having to sit down to urinate would certainly suck.
Assuming my body reformed itself to look like something more feminine than a 6-foot weightlifter (I suppose I'd look like my sister), none of my clothes would fit properly, nor my shoes.
I wouldn’t look much like my ID photos, and you can imagine the nuisance of trying to get those changed… “Yes, this old driver’s license is for a 6-foot man, but now I need it to say I’m a 5’5” woman. I’ll need a new photo, too."
If my body did NOT change shape much, then I’d be a fairly unattractive woman, what with my manly shape and big feet and so forth. I suspect this would hurt my career prospects.
As irritable as I already am, I hate to think what I’d be like with PMS.
What is that ping pong ball trick?
Visit a doctor?
Curl up in a little ball & whimper, due to a case of castration anxiety that Freud wouldn’t have touched with a ten-foot couch.
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Enjoy being a first class citizen for a change.
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Spend all the extra money I’d be making.
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Get a promotion.
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Buy a car/go to a mechanic without getting screwed over.
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Masturbate. (Strictly for scientific purposes of course–to see how orgasm feels from a guy’s prespective. :D)
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Walk around shirtless…no…better…run around shirtless, now that I’d be breastless and subsequently, able to run properly.
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Lift something heavy.
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Desperately wish to be female again.
I’d go out driving really fast, because I’d know that a conjuring up a few tears would get me out of a ticket.
Then I’d go see how nice the ladies’ room in a fancy restaurant is.
Stand in front of a mirror for a bit.
Maybe then do some ‘exploration.’
Walk into a changing room or two.
And then finally realising that I wanna be a guy again.
You see, when a woman and a ping pong ball love each other very much…
No, seriously, it’s when a woman shoots a ping pong ball out of her vagina. I don’t know if it’s ever been done in real life, but I’ve seen multiple movie references to it, so you never know… 
Ha. Haha. Hahaha. For many. Many. Hours.
start the coffee—turn on the computer—click on SDMB—and post:
"Help! I woke up as my opposite gender!"
Re-watch the movie Switch and try to not make all the mistakes Ellen Barkin did?
Pee standing up, preferably in a semi-public manner.