Act Out Meaning

(idiomatic) To perform a fantasy in reality.

Example: Used other than as an idiom: see act,‎ out.
  She's a street performer, so she acts out on Ninth Street.
To perform something specific.
  Despite already being aware, he will be acting out the pretence of a surprise.
  I've wanted to do this for so long, but I never thought I could act it out.