You could keep it nice and simple, whilst wearing a nice set of perv gloves (most tight shiny brown leather ones typically look the part, nothing says perv more) stroke her face, then give a big smile with some sort noise to denote your satisfaction/ecstasy and then just walk away. No words needed, should be weird enough, if not perhaps work in a sniff of the neck first, like a dog sniffing anothers backside.
Fill your pockets with spaghetti, talk to her in the most socially awkward way you can, make the spaghetti fall out your pockets. Collect spaghetti from the floor in a panic and put back into your pockets.
Indirect approach, chat to targets best friend dropping hints that you like target, then leave gift on desk for target, perhaps these with some pubes for effect and a note to suggest you are always thinking of her and this is something to keep you in her mind
Just to be clear too, you can't reveal to the person you are wooing who you are! They don't find out til the end of the week!
Is this just a bit of fun between close colleagues, all agreed up front and opt-in, like secret santa? Or is this something officially sanctioned by the management? 'Cause if it's the latter... If this was going on at my work you'd better believe I'd want to opt out, or I'd be right on to HR. It also sounds like it's totally straight (guy has to woo girl and vice versa) which might not be fair on some of the participants!
I attended a mass 'wedding' one time where the 'couples' were drawn out of a hat. I ended up with a dude . Sad part is, it's probably the closest I'll get to actually being married. Still, this sounds like a horrible idea. You do still have to work with these people after all, and that's not going to be easier if you creep them out.
An eye mask with the word BEAUTIFUL written on it, with a note that says "You're beautiful when you're sleeping." I think that fulfills the creep factor for you.
Put a webcam on her work desk and put a postit note on her screen saying "i'm watching you" Get some pictures of her from facebook and cover a colleagues desk with them. Place them around the office also. get a rose and spray paint it black. While it could be funny. It can also backfire sooo much it's untrue. Especially with a female colleague. I would make someone else aware of what was going on before you did anything.
1) Mention that you like [insert animal here] 2) Show her pictures of said animal and see if she likes them. Tell her you really like those animals. 3) Pick a specific picture of one of the animal. Send it to her and tell her you think it's hot. 4) Mention that you think of a famous animal ( Brian Family Guy, Spiderpig etc) when you're in bed. 5) Ask her if she likes any animals. Try not to get fired Parge
I would leave a card on her desk with the following, "So after talking to your parents at the weekend, they've agreed that we've worked together long enough to progress onto marriage. P.S having pulled your personnel file to find your address I shall be around later to drop a few things off, like my Hi-Fi and sofa. Do you really only earn that much? I'll have a word and see about bumping you're salary since I plan to quit soon and you'll need the extra money to support us."