"Sending a Lover".
According to the query on NetEase Cloud Music, the boy my little sister sent me (yoyo) is a lyric from "Send My Lover", which is a song sung by Yue Yunpeng and Good Sister, composed by Qin Hao , anonymously composed lyrics and music, included in the album "Sending Lover".
Part of the lyrics: My little sister gave it to my husband (yoyo); I sent it to the south of the gate; I took out two big silver dollars from my waist; I left this dollar for my husband; Buy a train ticket.