This describes a
condition where the
subject sits
motionless with
eyes wide,
staring glassily out at the world like one of those freakish
Precious Moments ceramic figurines.
While this condition often denotes a complete lack of mental activity, often caused by too much time spent watching television, it can also be caused by an extremely high rate of mental activity, such as when you've been caught in the act and have to come up with a plausible explanation before everyone figures out what it was you were really doing.
This condition is very similar to going tharn.