Your thread title says yours, the body of the message says your friend's. Which is it? We generally don't discuss what might be seen on some else's phone, if it's actually theirs you could ask them. If it's yours and on the left side, pull down the notification shade and see what app might be associated with it.
If you need additional help or have more questions or details to share, please join the site so you can reply in this thread. See
this link for instructions on how to join Android Central.