Not as hard as it seems. Obtain the Hot Rod item during a race and use it. You will notice it starting to shake and smoke rising from it as well as the boost getting faster as the seconds progress. When it starts to look like it is going to explode (smoke flying out the top and the Hot Rod shaking uncontrollably), press the A button and the achievement should unlock. If it is not done at the right time the Hot Rod explodes and damages you.