Rumer Willis eats condoms

Rumer Willis, the eldest daughter of Bruce Willis and Demi moore found putting condom in her mouth. Rumer Willis, is not as famous as her father or her mother but she is daughter of Demi Moore and Bruce willis makes her famous.

But I have a question, do you at condom to prevent STD and AIDS before you have sex. As for as I know condoms are need to be used in Vagina or in penis not in mouth. Then why did Rumer Willis, is eating condoms. Can any doc, help me in understanding the concept of preventing AIDS please

Image source thesuperficial