Would this be a majorly weird thing to ask of my sister?

Okay so this is a really embarring thing to ask on Y!A but here it goes anyway......Do you think it would be okay for me to ask my sister to buy me a vibrator for my birthday? I'm nearly 16, she's 23. I do not have that good of relationship with my parents, they would kill me if I asked them (not literally) and I would be to embarred to ask them anyway!