Swine flu.

C’mon people, all you technical players and bulls out there have put your money on the riskiest bets since the March 8 low. Bets like retail, home and commercial real estate. Get real.

You’re probably already worried about your long positions. Technicals indicate we’re overbought. Optimism is the highest since 2003. Up volume is weak. Earnings multiples are too high during this ending (as some of you believe) recession.

But swine flu will kill your portfolio. It is no black swan: billions of people will be exposed to a flu virus, not vaporized in a nuclear blast. But the virus is hospitalizing too many folks, too many of those affected are in the ICU, and the northern hemisphere is experiencing flu season way too early for investors to underplay swine flu. (Weekly update from WHO)

Cooler heads around the world will be staying home when possible and donning N95 masks when out. Those of us who like to ignore bad news (hello, America!) may lead everyday lives longer, until changes at schools and hospitals become too big to ignore. That just means the investing tide will turn faster, especially when nerves are already jittery in October or November.

Want to park your money in a long play? Try home-shopping and park-your-butt-on-the-couch plays like E-Bay (EBAY), Amazon (AMZN) and Netflix (NFLX).

But when the return of the secular bear combines with swine flu fears, money could hit the sidelines like it did in September 2008. If you’ve got the stomach for it, go short on retail, commercial real estate and commodities. Gold bugs will keep gold above $700, but silver and the car metals like palladium will dive.

Timing the market right on short CRE plays could still kill you, even if you’re ultimately correct. Consider double-short (SRS) or triple-short CRE (DRV) like playing an aggressive game of hearts – you’ve got a shoot-the-moon hand, but you might lose a point somewhere in the mix.

Go double-short on oil (DTO). Hurricane season is already a bust in the gulf, and inventories and capacities are simply too high.

Long plays are few and far between. Alpha Pro-Tech (APT) is a tiny company with no debt, a (barely) positive earnings history, substantial N95 mask business, and enough other products to provide some protection in case the swine flu play is wrong. Tread carefully, however: the stock has already moved huge this year, and its share price is just entering the shark waters around $5, when margin buyers and shorts can wreak havoc.

One final word: if you’re too conservative to try these strategies, watch the VIX. When the VIX is low and up volume is light, go for it. You’ll miss out on leading indicators like oil (already falling), but I imagine that big banks and private equity will try to prop commercial real estate as long as possible before throwing away their hands.

Disclosure: Long SRS, DRV and APT