only one meaning fits the time that the phrase became a popular expression, not old England or something in the backseat of a '55 Chevy. as a Vietnam vet i was there when and where it started. we all used the expression "it sucks" to describe something really bad as in a 'sucking wound' ie a open chest injury where the lung was exposed to air and sucking noise was what you might hear just before someone dies. thus a sucking sound is a number 10 as in a bad, bad thing.
why this is important is that if by some unfortunate situation you come upon a injured person with a open chest cavity be so kind as to carefully place something over that would that limits the open lung from sucking in air, blood and perhaps a few other items. then scream for medical help, CPR, or anything else that is less primitive. on too many battle fields now and then we humans are doing awful things to each other and it would not hurt if we all had a little more knowledge not just about what sucks but what do humans need to to grow up and reduce these suicidal tendencies of killing off our species.
that is my 1.5 cents worth and only a future of an even more unstable currency where my 2 cents becomes even more worthless is what really scares me. have faith, live well and support our species. ken