Mysterious "On My Way" Ping appeared...I was the only player and didn't do it! Spooooky
http://i.gyazo.com/d0a53c24eef915dd10779aede7e0ee78.gif http://i.gyazo.com/cbccebce6a334623c3bb7c22b9aa1a77.gif
You can see my cursor is just clicking to attack minions, but an on-my-way ping not sent out by me appeared just inside the enemy base, which you can see on the minimap. There was no message in the chat like you'd see if I did the ping myself (I checked right after just to verify).
Was just screwing around in a custom Me vs. Soraka Bot match. I wonder, what caused the ping?

Edit: It seems as though the Rift Spirit (the roaming ward you get for Smiting Wolf) pings when it heads to an enemy. Didn't know that because I don't usually jungle. Odd that it pinged to the inside of their base though...