腦殘 [nǎo cán] adj. Brain+disabled. Literally “brain-damaged”, this slang term is often used to laugh at a person who is ludicrous, dumb, or weird.
Actually Xiaoming is the most 2B kid in China. He always topples the ink [bottle] and then let us calculate the stuff inside [meaning the numbers covered by the ink]. He never solves a problem and always asks us to correct the mistakes for him. He always forgets to bring things and asks us to figure out the time when he arrives home to get the things. He always likes releasing water from and adding water to a tank at the same time. He always likes chasing his Xiaohong on his bike…who can beat him in terms of forgetfulness and dumbness?
[Note: This quip is related to the Math assignments at Chinese elementary schools experienced by Chinese young people born in the 1980s and the 1990s. “Xiaoming” (boy) and “Xiaohong” (girl) are often featured in math problems. The scenarios mentioned above are not uncommon, either. For example, students are asked to figure out the missing numbers of an equation tainted by ink, the time spent on the way because “Xiaoming” has to return home to bring something, or the time spent on filling a tank which is slowly drained at the same time. The tone of the quip reflects a hint of nostalgia rather than sarcasm.]