Catch Off-Guard
Foes are surprised by your skilled use of unorthodox and improvised weapons.
Benefit: You do not suffer any penalties for using an improvised melee weapon. Unarmed opponents are flat-footed against any attacks you make with an improvised melee weapon.
Normal: You take a –4 penalty on attack rolls made with an improvised weapon.
Source: Pathfinder Core Rulebook, p. 119