As an audience for great live performances, people usually act as a passive spectator or interacting poorly with the performance themselves. Typically, the audience feels the need for higher engagement in these events, what happens spontaneously in some creative ways, but in a very superficial and uncoordinated way. This work deals with coordinated human interaction in live performances using smartphones for creating special crowd effects, fostering a more active people participation during the performance. To encourage this behavior, we developed a coordinated approach using mobile devices with offline vs online and synchronous vs asynchronous visual effects. Considering that the great majority of the public already has their smartphones, our solution is cheaper than giving an armband for every person and can provide the same engagement feeling and more dynamic effects on the crowd.