Mega Coin Squad

This is only possible in Green Valley 1-1, as progressing to any further level requires collecting coins. To do this, find a way to die in the very first level. You will likely only have up to two options: a turret that shoots bullets in a single direction, and a small, crawling creature. If either of these things are not immediately available, wait for a new structure to spawn, and these enemies may spawn with it.

Once you have one of these options, simply walk or jump into the enemy (walk into the creature, or jump into the bullet from underneath or beside it) to hurt yourself. While doing this, be sure NOT to collect any coins that may be nearby. Defeating the creatures may also spawn coins, so if you defeat a creature by accident, be sure not to pick up the coins that fall. Hurt yourself 3 times to kill your character, and, if you haven't collected any coins by the time you die, you will unlock this achievement.