1 - A tactic for use in dire circumstances.
2 - When there seems to be no reasonable resolution to a situation, creation and implementing a very extreme tactic.
This derives from the actions of a squirrel when it is cornered with no reasonable method of escape. The squirrel will then use any method possible to escape.
Johnny fought three men at the same time last night. When he saw he was outnumbered he turned to squirrel tactics to fight the men off.