ptASSd
Post Traumatic Ass Disorder. A constant, irrational fear of your ass being harassed in a wide variety of ways, due to an inordinate amount of grabbing, spanking, poking, etc by your friends. The most common observable symptom of ptASSd, is never turning ones' back to anyone EVER, and NEVER bending over within anyone's reach, even if extremely inconvenient, so as to avoid a pen or pencil from being slipped into their buttcrack for example.
After 15 solid years of our butts getting poked and grabbed by everyone else all the time, our circle of friends all suffer from ptASSd.