GW2 Don’t Be Rude to the Brute achievement, you can acquire at the end of Aetherblade Retreat instance.
This is the easiest achievement you can acquire in Aetherblade Retreat (if you ignore the fact that you should defeat Champion Frizz in order to reach Horrik). In the last room, simply target Horrik, type /salute in the chat box, hit Enter and enjoy your 5 Achievement Points.