Yet Another Grand Exit. The YAGE is the dramatic thread or post that someone makes when announcing intentions to stop posting on a forum. A typical YAGE involves both insulting other forum members and the announcement of having better things to do with his/her time than post on that forum. Generally, it's followed by "No! Don't go!" from some and some variety of "good riddance" from others. In almost all cases, the author of the YAGE returns in some form or another.
Did you see Carl's latest YAGE? He'll be back in a week.