1) in literal terms, putting your mouth to an anus and quickly inhaling, causing a stream of air to be pulled into your mouth from the anus.
2) in slang terms, to be bad. This is how the phrase is most commonly used, and tends to be more intense than the usual "that sucks." "That sucks ass" is like adding a "really" to it.
"Not like that, man"
2.) Used as an expletive in the areas of #1
Someone who thinks if they kiss the right ass, it will get them somewhere.
A yes man.
Someone who sits in the supervisers kissing ass in the office everyday trying to get a salaried job.