“If you want people to like your food, make it free.” If that isn’t already a whimsical tidbit said by someone’s grandmother, it definitely should be, because oftentimes it’s true. From showing your affection for a special someone to getting people to show up to meetings, the promise of free food is a tried-and-true way to make people happy and get a party going. The Boston Public Market — the indoor, locally sourced grocery mecca run by foodies, for foodies — already has a knack for having some of the best food and produce in town, so what’s the one way to make their culinary offerings ever better? Well, like someone’s grandmother probably said, make the food free — which is exactly what’s going to happen at BPM’s second annual open house. The event will feature a literal smorgasbord of the best BPM has to offer, from food demonstrations to pop-up vendor booths to, of course, free samples. You can also try your hand at some food trivia, take advantage of one-night-only coupons, enter a giveaway or two, and even take a break from stuffing yourself at the beer and wine bar (that will require cash, however). Guests will also receive exclusive BPM “swag bags,” and will be automatically entered to win a $100 on-the-spot shopping spree. For those keeping track, that’s free food, good company, and the chance to win even more food. Not bad for a near-penniless night out. No RSVP is required, so show up with a stomach as empty as your wallet. Tuesday, March 13, 4-7 p.m. Free to attend. 100 Hanover St. at Haymarket Station, Boston. For more information, visit www.bostonpublicmarket.org or call 617-973-4909.