Freaked out of his bird?

[coolfool]

I don't understand the following highlighted parts:

In fact, some of the things you see in the film - like my looking away and trying to keep myself from breaking up - were caused by my looking at Denis off-camera over in the bushes, totally freaked out of his bird, laughing his head off while I'm in there trying to do my Lyndon Johnson and keep everything together. - page 168, Jack Nicholson, December 2012, Playboy

I can't figure out the exact meaning of the former and guess the do of the later may mean act but ain't sure.

Please lend a hand. Thanks a lot.

[Tdol]

My guesses:

1 Under the influence of drugs
2 Behaving like Lyndon Johnson, who became president after the assassination of JF Kennedy, so had to try to keep things calm in difficult times

[Gillnetter]

I don't understand the following highlighted parts:

In fact, some of the things you see in the film - like my looking away and trying to keep myself from breaking up - were caused by my looking at Denis off-camera over in the bushes, totally freaked out of his bird, laughing his head off while I'm in there trying to do my Lyndon Johnson and keep everything together. - page 168, Jack Nicholson, December 2012, Playboy

I can't figure out the exact meaning of the former and guess the do of the later may mean act but ain't sure.

Please lend a hand. Thanks a lot.

Totally freaked out = Lost control. Acting in a strange manner. Teenagers use the term "freak out" to mean that someone, or that they, are reacting to an event in an abnormal manner.
His bird = His mind.

[coolfool]

Totally freaked out = Lost control. Acting in a strange manner. Teenagers use the term "freak out" to mean that someone, or that they, are reacting to an event in an abnormal manner.
His bird = His mind.

Would you please prove his bird means his mind?

[Tdol]

It's slang:
Urban Dictionary: Out Your Bird

http://bird.urbanup.com/1750286 (This link uses the word mind, but also contains swearing)