Boyfriend/girlfriend drop refers to the act of subtly adding the fact that you have a boyfriend/girlfriend into the conversation in order to deter anyone who is potentially interested in you.
“扔男友/女友”指在聊天的时候不经意提起自己有男朋友或女朋友的事情，目的是为了击退某个对你感兴趣的人。
For example:
She thought I was interested in her and boyfriend dropped me in our last meeting.
她以为我对她有兴趣，于是在上次见面的时候就告诉我她有男朋友了。
这个说法大概是来自于英语中另外一个使用较广的表达name drop，名词形式为name dropping，也就是我们平时说的“拽人名”。
Name dropping is the practice of mentioning important people or institutions within a conversation, story, song, online identity, or other communication.
Name dropping指在谈话、故事、歌曲、网络身份或者其它交流中提及重要人物或机构的行为，即“拽人名”。
Name dropping is used to position oneself within a social hierarchy. It is often used to create a sense of superiority by raising one's status. By implying (or directly asserting) a connection to people of high status, the name-dropper hopes to raise his or her own social status to a level closer to that of those whose names he or she has dropped, and thus elevate himself or herself above, or into, present company.
“拽人名”通常是为了在某个社会层级中确立自己的地位，通过提高自己的地位来建立一种优越感。这些人在暗示(或者直接表明)自己与高层人士的关系时希望能够将自己的社会地位提升到与那些高层接近的状态，从而凌驾于身边同伴之上，或者成为与其平等的一员。
