Improving yourself in someway. To strive to become the unicorn you've always wanted to be. Setting your goals high and doing whatever it takes to reach them.
Friend1: "Man, Sally has really been working out lately and even ran a marathon the other weekend."
Friend2: "Yeah, she's really getting her unicorn on."
Girl1: "I wanted to sell 100 boxes of cookies this year but I only sold 25."
Girl2: "Sounds like you weren't getting your unicorn on, huh?"
Guy1: "I'm going to have sex with every girl in this club tonight. I'm getting my unicorn on!"
Guy2: "Yeah! Let's do it!"
Lady1: "You're using that phrase wrong!"