[xXthefragileXx]

Originally Posted by Nozza x360a

Up High, Down Low 15
Gave Claptrap a high five

You'll first get a chance to high five Claptrap in Sanctuary where he's located in the north west corner of the map. He'll also offer you the mission "Claptrap's Secret Stash".

You'll first need to complete the mission he hands over to you, which isn't very hard. Once done, turn it in and then follow him. He'll only walk around the corner to another NPC. Once he does, get close and you can then press to give him a high five.

Simply press and Claptrap will then put his hand up in the air. Now aim up and press to melee his hand for it to count as a high five. It may take a couple of goes to connect, but once you do, he'll put his hand back down and the achievement will unlock.

Borderlands 2 - Up High, Down Low Trophy / Achievement Guide - YouTube

Just a side note you may want to add on this one. When you turn in the mission, the claptrap talks to you for a bit then begins wandering all over Sanctuary, stopping only briefly in a couple spots, making it quite difficult to give him a high five. He will put his arm down after about 20 seconds or so and the option to give him a high five goes away. I dashboarded out, reloaded and redid the mission and got it by cutting him off (like in the video)