Suck can be used as a verb or noun regarding using the mouth to get a liquid. For the meaning you mean, it is an informal way to say something is bad - bad quality, bad situation, bad at doing something, etc. This sucks! This is terrible! I suck at sports. I am not good at sports.

It is one of those words that everyone uses but it comes from a very vulgar expression. Basically, it comes from a slang term for giving a man oral sex. Even in it's vulgar form "sucks cock", it still generally means the same thing. 1) Something is unfortunate. I heard you failed the exam. That really sucks. 2) Low quality That new television I bought really sucks. 3) Unskilled I really suck at writing poems. An alternate form of "sucks" is the word "blows" which also stems from the same vulgar term as it also means fellatio.

"Suck" is one of those odd sanitised or softened vulgarisms. In this case, the vulgar part is omitted and sometimes even the implication of fellatio is lost. Or denied? A couple of other sanitised expressions I can think of are "mofo" and "to brown nose".