UNTRANSLATABLE

“Kos Ki” has been around…possibly since time immemorial. “Kos Ki???” started circulating online thanks to the Bangladeshi blogosphere and attained wider usage through Facebook. Numerous memes have been created using “Kos Ki???”. At times it's more effective and apt than its supposed English counterpart, “Seriously???”
Example: “You gave a presentation, in front of the whole class, with your zipper open? Kos Ki???”