definition consistent with whatever but with the addition of the 's', making the plural version (whatevers), gives more emphasis to the meaning. whatevers is used as an adjective to describe the insignificance of something or it can be used to express a more passive form of disgust or loathing for something.
"dude, that gay biker gang that just left took the last of our beer."
"fuck. that shit is so whatevers, man."
"wesley, why are you still wearing nail polish? halloween ended three weeks ago."
"whatevers, dude. whatevers."