A Dutsklutser is someone who defeats an entire team in a round of CS:GO. Originating from The Netherlands where it is a portmanteau of the words "Duts" (=dutch) and "Klutser" (= Clutcher).
Another form where it can be used is as a verb, this would make it: "You have geklutst", meaning "You have clutched".
"Let me ace bro, I only need one more." "Damn bro, you about to be a Dutsklutser."