auction of promises
noun [ C ] uk/ˌɔːk.ʃən əv ˈprɒm.ɪsɪz/ us/ˌ ˈɑːk.ʃən əv ˈprɑː.mɪsɪz/
（常以慈善募捐为目的）竞拍
an occasion when people bid (= offer money and compete against other people) for something that someone has offered to do, for example cook a meal, wash a car, etc. It is usually done in order to get money for a charity.