What should I

[FlyingJesus]

Maybe he's not into rock

You don't just use guitars for rock babe.

[Shawnstra]

I'd say get money, and then later decide what you wanna do with it

[lAdmire]

get for my birthday?!

It's on the 30th of April and I have no idea!
I'll be 15 and i'm your typical teenager.

Any suggestions?

Other than the obvious; MONEY! ;P

That's the only thing I would ask for. You get money && you can spend it on what you want.