In The Simpsons ep 'Children Of A Lessser Clod' it starts with a basketball match. Carl is great at this and sings 'Go Carl Go Carl Its my birthday Its my birthday.' These lyrics arre similar to the current 50 Cent track's chorus. Iss this any more than coincidence?
i'm not sure but i think u will find that " go ( whoever) its ure birthday" is an american saying or latest cool saying for " go for it " ( or thinking about trying to score with a chick) "(whoever) is in there!" check american pie for research purposes :-)