ANONYMOUSLYSend your package anonymously without them EVER finding out who sent it. Poor soul will be left powerless pondering until his/her end of days wondering who sent it because they will never find out with this option.
Send it Anonymously with an OPTIONAL "Ransom Fee" option (at no extra cost to you) that the victim has the option of paying to find out who sent the package. Prank them and make them PAY FOR IT! You get the money. The higher the ransom fee the higher the profit returned to you. The ULTIMATE prank/revenge. Not only did they get owned and pay for it, but if your ransom fee was set high enough you could even PROFIT!