Originating in the game of tag, no backsies is a maneuver in which a player that is "it" cannot be tagged back immediately following the tagging of another player.
No backsies can further be extended into the real world, where people use "no backsies" as a means to avoid doing a task.
To invoke the rule, one must simply say "no backsies" before the item or action in question is returned to its original source.
Example 1: Alice, Bob, and Corey are playing tag, and Alice is "it." Alice proceeds to tag Bob, making him "it." Bob turns around and tags Alice right back. Alice neglected to say "no backsies," and is now "it" again. Bob would not make the same mistake. As his hand touches Alice's shoulder, he screams "no backsies." He then proceeds to punch her in the face for good measure. Bob cannot be tagged "it" until Corey has been tagged. Which won't happen. Alice is in the hospital.
Example 2: Alex and Daniel are arguing over whom has to put away all the toys back into the chest. Their mother comes in to threaten them that if a certain thing isn't put away within the next minute, they would both get in trouble. Obeying the unwritten rule that the last one to touch something must put it away, both proceed to argue over who actually touched it last. Daniel picks it up and throws it at Alex, hitting him in the face, and calls out "no backsies." Alex, now bruised from the padlock that their mother wanted put away, now has no option but to return the heavy metal object back to the toy chest.