In the summer of 1984, we were introduced to Gizmo, and by winter of that year every child wanted their own mogwai for Christmas, just like Billy Peltzer in Gremlins. In the Joe Dante-directed movie, the mogwai is discovered in Chinatown by Billy's father, who wanders into an old shop where he tries to sell the owner on carrying his "Bathroom Buddy" invention. Instead, he leaves with a mogwai that he calls Gizmo.
When the movie first came out, it was a little unclear if this was supposed to be New York City's Chinatown or San Francisco's Chinatown. In the review from the NY Times that year, critic Vincent Canby believed it was the latter, writing: "At the beginning of the film, when Rand Peltzer, an unsuccessful inventor, buys a mogwai in San Francisco's Chinatown as a Christmas present for his family." We await the correction, however—while Peltzer was on a trip trying to sell his invention, it appears he was visiting NYC, which was closer to his fictional (likely Upstate) hometown of Kingston Falls. This is what's projected in other synopses and reviews, including the one on IMDB, and was confirmed in Gremlins 2 (which took place and was filmed in NYC). In the sequel, the evil developer Daniel Clamp (based on Donald Trump) offers to buy Mr. Wing's store, where he wants to put up a new development.
Regardless, the original mogwai is purchased in a Chinatown that was created in the Warner Bros. Studios backlot in Los Angeles, making it ambiguous enough that whatever Chinatown you were near to as a child was definitely the one where you could find your own personal Gizmo.
Recently, we spotted the above photo on street artist Hanksy's Instagram feed, but it turns out Chinatown proprietors aren't putting the signs up because of a nostalgia-driven uptick in requests for the creature. The drawing was simply a little joke from Hanksy himself, for any passersby who still have one on their holiday wish list. He tells us he put up three along Canal Street, and this one was near Orchard Street.