To be 'Freebirdin'' or to 'Freebird', one must be listening to the song Freebird and be doing something extreme or exciting without thinking about the next move you will make in that activity. The activity may be in real life or in a video game.
"Damn, I'm bored on this drive. I'm gonna do some drifting and be Freebirdin' it.
When a man takes off his pants and under garments, but leaves his shirt on. His testes are said to be going freebird since they flop around in the cool breeze when he walks. This commonly occurs in locker rooms outside of pools and gyms, especially with old people for some reason.
Mike: "Oh my god there are so many old people here going freebird! Save me!"
John: "Hell no I'm not going in there! I don't need to see old people's balls! You're on your own."
One who lives on your couch or in your garage for free. He only only leaves if you start working or cleaning around the house and ask him/her to help, or there are no free drugs available.
Don't pass that to Freebird, she never contributes!