1. Buy a couple dozen carnations (or roses if you're rich) and walk around the neighborhood. Scope out the loneliest looking girls and give them one. This will make them very happy.
2. Call ALL of your ex-significant others at around 11 PM and drunkenly tell them how much you love and miss them. If they say they miss you too, hang up immediately and proceed to number 10.
3. Make a trail of Hershey's Kisses (or another candy of your choice) and make a trail around your house. Wait a few hours, then go follow the trail! It will be exciting even though you did it yourself.
4. Go out to a fancy restaurant, ideally of European inspiration, and hit on the hot foreign waiters. Yes, you can do this even if you have a hot date, but beware: All the single people eating by themselves will resent you, as if they don't already.
5. Wear black.
6. Watch a slasher film with your dog or your mother.
7. Wear red and green and carry around mistletoe. Walk around yelling "Happy Christmas!" and hold the mistletoe over you and everyone you talk to. Demand a kiss. If they don't give you one, kick them in the shin.
8. Cross-dress. When you get asked what the hell's going on, act like you have no clue what they're talking about. Then ask them what they're doing for Valentine's Day and if they'd like to have a popsicle with you.
9. Buy yourself a three-pound solid chocolate heart, a giant teddy bear, a few cheesy V-day knickknacks, and whatever else you want. Walk around with them all day and exclaim how embarrassed you are! Or you could pretend to have a secret admirer. Bonus: Hire a barbershop quartet to come sing you a love poem in front of everyone.
10. Do the Lebowski Challenge.