2nd Most tedious achivement in the game, took me over 30 minutes to get.
You to have progress to the eS game of skate in the road trip part of the game, which is the last part of spain (5th city).
Then start a party skate game, with at least 4 players, the type set to competition or challenge. then eS game of skate as the level. Difficulty on casual.
Play as all the players and when you sucessful pull of a required trick fail it as the next player. ( i suggest preforming manuals and nose manuals to fail quickier). When 15 letters have been given out the achievement will pop up.
Unfortunately you have to select the stance for a every player, every turn. A slightly quicker way then pressing start on the board and then raising the nose, is to press start then A on a controller.