Novel luminescent "nano-bombs" based on a self-assembled system of carbon-nanodots, termed supra-CDs, are developed. The luminescence of these luminescent "nano-bombs" depends strongly on water contact; they show weak emission in toluene and decompose in contact with water, resulting in strong photoluminescence. Paper coated with these "nano-bombs" is successfully applied for water-jet printing of luminescence patterns and the mapping of human sweat-pore patterns.