What does DOA on the "Friends" theme song stand for?

Dead On Arrival.

Lyrics:
I'll be there for you
Friends Soundtrack, Theme)
by The Rembrandts

So no one told you life was gonna be this way
Your job's a joke, you're broke, your love life's DOA
It's like you're always stuck in second gear
When it hasn't been your day, your week, your month, or even your year, but...

Chorus:
I'll be there for you
(When the rain starts to pour)
I'll be there for you
(Like I've been there before)
I'll be there for you
('Cause you're there for me too)

You're still in bed at ten, though work began at eight
You've burned your breakfast, so far things are going great
Your mother warned you there'd be days like these
But she didn't tell you when the world was brought down to your knees that...

Chorus

No one could ever know me, no one could ever see me
Seems your the only one who knows, what it's like to be me
Someone to face the day with, make it through all the mess with
Someone I'll always laugh with, even at my worst I'm best with you - yeah

It's like you're always stuck in second gear
When it hasn't been your day, your week, your month, or even your year...

Chorus

DOA stands for "dead on arrival", which is a medical and crime term used to refer to a person who was already dead when EMTs or police arrived at a scene.

https://en.wikipedia.org/wiki/Dead_on_arrival

The terms is used in the "Friends" theme song, which is "I'll Be There for You" by The Rembrandts. The lyrics using the term are seen below:

"So no one told you life was gonna be this way
Your job's a joke, you're broke, your love life's D.O.A."

https://en.wikipedia.org/wiki/I'll_Be_There_for_You_%28The_Rembrandts_song%29
http://www.azlyrics.com/lyrics/rembrandts/illbethereforyouthemefromfriends.html