This may sound daunting at first but there is an easy way to get this trophy
When you meet The Dork for the first time if you stay in the middle on the bottom floor The Dork will constantly spam grenades that miss you.
Whilst this is happening the Electric prodding characters come out one at a time from the doors next to you which you can headshot easily, and as long as you don't kill the Dork they will keep spawning. You will know you've done a headshot when their heads literally come off.