The level is Track 2 "Acid Skips".
After the beginning of the level, go to the far right where you have to activate the switch. After you activate it, fall down and go to the right until you arrive in the place of the image.
Jump on the wall and pick up the Double Jump perk. Run back to the beginning of the level and double jump on the left, where the green gooey stuff is at. Jump on the wall and you will get the achievement and two perks.