I was going to try to use swagger on a Pokémon with own tempo so that it powers up it's attack, but I was wondering if fake out would go before the prankster swagger.
Fake out Fake out has +3 priority compared to Prankster which only gives +1. Source: http://bulbapedia.bulbagarden.net/wiki/Fake_Out_(move) and http://bulbapedia.bulbagarden.net/wiki/Prankster_(Ability)