Embarring Halloween costume issue? please help?

please please help me think of something else my sister could make me wear for halloween instead of what she has planned. i lost this stupid bet with my younger sister so now i have to let her decide whatever she wants me to wear for halloween and trickortreat with her and her friends. im 16 and shes 13 and i know if i was taller than her i would easily say no to her but since shes well alittle stronger than me cuz all she does is cheerleading and used to do gymnastics she can kinda force me to do whatever she wants me to. im short like my aunts and grandmas, 4'8" and shes tall like my parents 5'9" so her ideas so far is either making me dress up like a baby in pink pjs and diaper with a pacifier or wear one of her old cheerleading uniforms she used to wear when she was 9 and sadly fits me. she even wants me to wear girls underwear with the cheerleading costume under ies ugh. i cant do this, please can you think of any other ideas for her that would be alot less embarring for me? its gonna be embarring when she makes me trick or treat with her and her friends cuz theyre all taller than me and the people who'll give us candy will probably all laugh at me when they find out im 16