The TearDrop is a glitch in Dark Souls III which lets the player bypass killboxes by abusing the Tears of Denial spell.
After dropping down into a killbox, the game assumes the player died but instead survives the drop through the killbox with 1 health point, turning the player in a state of becoming invisible and showing only the glowing Tears of Denial effect.
In this state, all regular world collission is negated allowing the player to freely roam out of bounds.
Teardrop 1 by Fudgecow