Book-bag troubles PLEASE HELP!?

Ok, I'm in middle school (7th grade) and I have a dora book-bag and people make fun of me. I like dora and they always say im so kiddie and i like baby stuff. Its making me feel really sad. And I don't want to change my book-bag to a different one because that's what they want. And if i go to school with a different book-bag they'll say ''oh you finally decided to change that kiddie book-bag'' and then rumers will spread around the school. Everyone will know and blah blah blah you know the rest. But anways I was hoping that somone can tell me what to do so they'll stop making fun of my book-bag.