How to get your parents to let you get sims 3?

Well I have been wanting it since before it came out but my parents hate it since when I was about 7 almost 8 they got me sims 2 then I didn't know about the wah'hoo part I just knew in the game it made "Babies" so I did it in the game and I showed my parents and from this day on I am not allowed to play it I have waited without mentioning it for almost 2 and a half years I have even said since I had the 'talk' and it is under the covers I should be able to play it and i will not do 'it' but they said I can't play it because it has 'it' in there and that is final but im almost 10 and a half im very mature im the best reader in my cl I got a 20% higher score on both my math and reading test my mom would let me get it if my dad said yes but they both have to agree but I think it is unfair since I get GREAT grades I would pay for the game myself I would not do the bad thing im very mature and since I have been so kind to not mention it but I dont want to get them mad what do I do????