Ah, if this is in lime green text, then that would be the Group chat. If y'er not in a group, 'tis not unusual f'er people to get a random online status from an unknown person. Just a glitch in the clockwork, ye could say.
Other than that, I'm not quite sure what else that could be. I'm not quite sure what y'er wanting to do with it, by the way. This is just a notification that lets ye know someone has gone offline.
Perhaps ye can elaborate on what y'er wanting to do?