Definitions by gravy
You've changed
To be used half jokingly amongst friends; use when an acquiantance does or says something out of the ordinary.
Your wingman suddenly decides that he would rather sit home and watch a movie than head out to the bars on Saturday night. "Billy, you've changed"
You've changed by Gravy November 19, 2004
mullered
I've always taken it to mean generally either fucked up or fucked over. It doesn't have to be related to drink or drugs.