This achievement is done on the "Neverending Trials" skill game. In this skill game are you asked to complete small rounds, where you must jump over random obstacles without faulting. To gain the achievement, you will have to successfully complete 15 rounds. This achievement is extremely difficult, and you will probably spend a lot of time here. The only real advice is to keep trying, memorize the repeating rounds, and keep playing until you are graced with an "easy" set of rounds. Eventually, after trials and error, you will be given a set of random of rounds that are easier than usual.
I recommend the Phoenix 250cc, but the Banshee 350cc will also work.