The two codes seem to function as polar opposites, so you try using the 666 code on the same target to see what happens.

It turns back into a REGULAR DEAD MOUSE! Instead of making you feel FEAR or JOY, you mostly feel NEUTRAL, albeit a little grossed out. You guess the two effects just kinda cancel each other out. Well, at least now you know you have multiple options for disabling the horrific demon tentacles.