Not sure if posted before, but I'm asking this question from a Mathematica fellow user who tried to load expressions, whose problem soon turned into a prison break game featuring the following code.
SetAttributes[hold, HoldAllComplete]; GetOut /: hold[GetOut] := Unset[$Pre]; $Pre = hold;
After executing this code, all subsequent evaluations are hold, including the GetOut "key" and the reset expression.
GetOut $Pre = .
Are there any ways to unhold subsequent evaluations, in addition to rebooting Mathematica?