Choose the level "Party Bus" and the chainsaw character. With RB chainsaw a clear view. Look for a bomb in the item case, if it is not there quickly finish and try again. You must finish the level, fail, or fully quit to get a new level layout.
Once you have the bomb, slaughter until 1 victim remains. You can dance to annoy the last one. You need the last victim far to one side. Then quickly place the bomb, upon killing only yourself you get the achievement. Takes some tries but .