"it's my birthday" = pressies, or a check in the mail. a play on words, from some rap tunes of getting payed without actually having to work for the money.

Thank you! I honestly had no clue.

Yes, it's from a rap song, "We're gonna party like it's your birthday..."

I just saw the spot.. again... it makes me laugh but I don't really know why. I figured it must be derived from some popular rap tune. My Google search brought me here. Thanks for the answer!