The text plays on the word 'echo' which can refer to a sound that is reflected off a surface and heard again, as well as a feature in some online forums or discussion groups. Additionally, 'COURSE' is emphasized, which could be a play on words related to a course of discussion or a physical course that echoes. However, without additional context, it's not clear if 'echo' is being used for a humorous effect based on different meanings or similar-sounding words.
Of COURSE I ' m on topic . ( Which echo is this ? )