From China Digital Space
轻度追尾, 轻度 XX (qīng dù zhuī wěi, qīng dù XX): mild collision, mild xx
On September 27, 2011, there was a collision between two subway trains along Shanghai’s Metro Line 10. The collision injured hundreds of passengers and renewed concerns over China’s rail safety just two months after the Wenzhou train accident.
The evening after the accident, CCTV, Xinhua and a Shanghai television station all reported that “a mild collision occurred on Shanghai’s Metro Line 10.”
The claim that this was a mild accident elicited the derision of netizens who felt that the reporting was more intended to dampen fears about China’s train system than report what actually occurred. The phrase “mild collision” instantly became an internet buzzword and variants of the phrase began spreading. One parody was:
I awoke from a mild sleep, and felt mildly hungry. So I drank a glass of milk that had a mild amount of melamine and ate a couple doughnuts that had been fried in a mild amount of ditch oil. I burped mildly and then got onto a mildly crowded subway train. Sudden, I heard a mild screech and my head mildly struck the horizontal handrail causing mild bleeding. . . . There had been a mild collision.
A mild collision occurred on Shanghai’s Metro Line 10.
This was a "mild collision."