(1) verb: to send back something to a person that they originally sent to you; to return to sender
In reference to the Australian Aboriginal hunting instrument the Boomerang.
(2) verb: to quickly return something to the source
(1) Receiving a file back that you originally sent to someone, where the person who sent it us unaware they got it from you:
REPLY: "hey, thanks for boomeranging me that video, it's always nice to watch things twice :)"
(2) Used for sending someone back something intentionally as part of a reply to a message.
REPLY: "Good luck with the job Interview, and I can't help boomeranging this picture back to you."