Load up chapter 9, not the challenges. Select Bear Beard as your character. This is just so you can walk around without any hassle and he has good stats.
Play all the way through the level until you get to the part with the disco. Ignore all of the other bears and head down to the docks. As you are looking out to the water, the boathouse on the left has a toy chest out the the front. (right hand side of the door) Sabotage it and now wait for Giggles to come and fix it. When he does walk up behind him and kill him (RT).
**Giggles is the red bear with the pirate hat on (the one in the achievement picture)
**If any other bears start heading over hide in the bushes and Boo this will send them back the other way. If you do have to do that, you may have to quickly kill all the pirate bears as they may start trying to kill the normal bears.
**This may take some patience like the other Ironic Kill achievements, so don't give up.
If your achievement doesn't pop check out my solution for
The Giant pile of Gold achievement in Naughty Bear worth 155 pointsGot Gold Naughty Cups on episode 9 and all of its challenges. Yes, even the Top Hat Challenge!
There is a guide on what to do if your achievement glitches