Piggyback字面的含义是骑在小猪的后背上，字典解释是a ride on someone's back and shoulders.也就是我们中文里说的，背着某人，驮着某人。

to use something that someone else has made or done in order to get an advantage

沾光，搭便车

Everyone wants to piggyback on the phenomenal success of the TV series.

每个人都想借这部电视连续剧大获成功的机会沾点光。