To the uninitiated, the phrase “Big Yellow Duck” probably doesn’t conjure thoughts of revolution or social media-inspired uprising.

Yet China’s largest social media platform, Sina Corp.’s Weibo service, banned searches for that term and several others as the 24th anniversary of the infamous Tiananmen Square protests on Tuesday aggravated old wounds in Beijing.

Weibo, the Web service on which the term was banned, is a micro-blogging site that is best described as a combination of Facebook and Twitter, but that has more than eight times as many users as Twitter, according to Forbes.

Beginning last week, the site began scrubbing its search engine so that only approved results showed up when users searched for terms related to the protests. Monday night, censors opted to simply block the searches entirely, The Wall Street Journal reported.

So what does “Big Yellow Duck” have to do with the notorious June 4 conflict, in which the People’s Liberation Army injured and killed anywhere from several hundred to several thousand of its own citizens?

The answer has to do with the “Tank Man” photograph that comes to mind when most people think of the protests — a shot of an unidentified man standing unarmed in front of a line of tanks in Tiananmen Square — and a series of subversive re-imaginings of it that have cropped up recently as citizens find imaginative ways to get around government censorship.

In one of the most popular and striking of these edited photos, the tanks are replaced with images of giant yellow ducks — the rubber bathtub variety.

The ducks themselves are a reference to a real-life massive yellow duck that has been floating in Hong Kong harbor for all of May. Part of an international traveling art installation by dutch artist Florentijn Hofman, the ducks are well-known and well-loved throughout China.

Though the duck photo is probably the best example of the outlandish lengths to which censorship is taken in China, other search terms such as “64” for June 4, the anniversary of the protests, also returned no results on Sina’s Weibo, the South China Morning Post reported.

The phrase “Black Shirt” was also blocked after an online movement sprang up in which citizens were encouraged to commemorate the day by wearing black.