Pi Yan is a homophonic terrier, the latest network term. Pi Yan actually refers to "human chrysanthemum", that is, "asshole" In terms of network communication, it is uncivilized to use "asshole" and it will be rude and impolite to communicate, so everyone uses homophonic stalks and replaces "asshole" with "skin swallow". There are a pair of bloggers abroad who imitate dogs and like to smell things, carry out "crazy smell attack" on dogs and treat them as dogs. As we all know, dogs like to smell the same kind of piyan, which is one of the main social ways for dogs and a way to find heterosexual partners.