We’re always looking for something weird and fun to do indoors on the weekend. There’s no shortage of weird and fun things to do in this town, but rare is the weird, fun thing also simultaneously a terrific charity event. One such affair on our agenda this particular weekend is the 20th annual Canstruction competition down at the World Financial Center. Here’s the deal: it’s a contest where 25 leading architecture, engineering, and design firms are enlisted to transform more than 100,000 unopened cans of food into larger-than-life pop art masterpieces like this one.Each of these design firms have spent months planning their entries but are allowed only one superfreakout night to meticulously stack and color-coordinate their cans into ingenious feats of engineering. Are you listening, Bravo? Why isn’t this a reality show? Regardless, it’s exactly the kind of supernerd stoner thing that will no doubt produce some bizarrely clever pieces of transient art. And the feelgood kicker is, at the end of the exhibition the structures are dismantled and all the food is donated to City Harvest. At last year’s Canstruction, 73,970 pounds of food were collected, translating into nearly 74,000 meals for the city’s hungry.Admission to the show is free, but all visitors are asked to bring a can of “high quality” canned food (no spaghetti-o’s, I guess) to the exhibition’s collection station to reach a goal of collecting over 50,000 pounds of non-perishable edibles. Do good for humanity! See gigantic ladyparts comprised of tin cans! It’s a win-win this weekend for the Cold Weather Companion.