Yeah, I get what it means “woops, my mistake” however, where did it come from? I don’t watch a lot of network TV and I feel like I’m missing something here! 
Thanks!
I have no idea where it came from, but I find it deeply irritating. It sounds inane, IMO.
Been there, done that, if somewhat inconclusively:
http://boards.straightdope.com/sdmb/showthread.php?threadid=39915
is that it is most likely a contraction of “Am I bad?” At least that’s how I interpret it. Meaning “I have made a mistake and realize my wrongness.”
someday i’ll write a book on the wonderful world of urban playground basketball. i’ve spent all my years on the playgrounds of Los Angeles and Oakland, so i consider myself a little bit of an authority.
“my bad” comes from the habit of shortening all communication on the basketball court to the fewest possible syllables.
when you throw an errant pass that glances off a teammates hands, you could say: “sorry about that, guys. you might have been able to catch that pass, but it’s really my fault. i take full responsibilty for the mistake. let’s not place blame and we can move on from here.”
or you could communicate all those very things in 2 words: “my bad.” i guess “bad” is a more interesting translation of “fault” in that statement.
other translations:
traveling = walk
the ball went out of bounds off the defensive team = stay
you fouled me but i’m still going to make the basket = and one
you’re both on the same team, stop fighting over the ball = same
and numerous other examples.
i’ve been hearing this since the very early 80’s so i guess it’s about time it finally migrated, as almost all American slang does, from the Black universe into the white one. of course, now it sounds so cheap and stupid. what a shame.
Finally, a fellow blacktop baller on the boards. A couple of others that had differing levels of use in our games
Toast - When you make someone look really bad on a move, you have burned them.
Face - Pretty much the same as toast, used mainly for deep jumpers
Check - Used to let everyone know a play is about to begin after a dead ball at the top of the key
Although i grew up in suburbia and i hate basketball (even though im 6’5") I heard this term used at least as far back as 1987.and frankly it frustrates the hell out of me that so many people just dont seem to get it. Its a pretty self-explanitory phrase, like someone above said, it just means “my fault”. I had a boss a few years ago that looked at me like i was an alien everytime i said this. No matter how many times i tried to explain it to him he just didnt get it. Let me try and break it down for you…
A “bad” (a fault, a mishap, a mistake) occurs.
I (my) take the blame for it, as opposed to calling it your bad. Therefore you’re just saying…“oh, that wasn’t your fault, it was mine” My bad.
Looks like we think alike, BunnyGirl…
According to Kilt-wearin’ man it’s from the U.S. military, maybe as early as the 1950’s, but we didn’t get any confirmation of that. (I promise not to flirt this time and kill off the thread.) OK… So does anybody have an actual cite? Or actually used it pre-1970’s?
Here’s the latest in the on-going search:
do i get a little gold star for the best answer? 
oh, and Mullinator, my favorite synonym for “face” was always “ass.” best to whisper on your way back up court…
I took a look at the American Dialect Society’s email discussion on this topic, and it did not appear to be particularly rigorous in its examination… See for yourself at by entering “my bad” into the search at:
http://www.americandialect.org/adslarchive.shtml
While the urban basketballer explanation does seem to be the popular one, it might be a little hasty of us to consider the case closed.