U.S. Border Patrol agents freely used the derogatory slur "tonk" to describe unauthorized migrants on government computers, at times while joking about killing or beating them, according to emails and text messages disclosed to HuffPost under the Freedom of Information Act. The documents, from 2017 to 2020, reveal yet another instance of the Border Patrol's use of a slang term that officials in Washington have condemned but have struggled to stamp out. This is the second disclosure that Border Patrol personnel used the word in internal communications since HuffPost first requested a global search of its use among Border Patrol agents four years ago. The origin of the term is uncertain, but most insiders believe it comes from the sound made by bashing an arrested migrant's head with a government-issued flashlight. Some of the records reference that origin story, with one agent writing: "ah, savor the sound." Use of the term remained surprisingly common among both rank-and-file agents and those in leadership positions, the records show. Many agents appeared to use the term as a synonym for unauthorized migrants, with little apparent derogatory intent. But the slur often appeared alongside expressions of raw contempt for the people whom Border Patrol officers police. Border Patrol agents who used the slur at times gloated about migrants' misfortunes or made references to beating them. In one instance, agents joked about killing migrant children in their custody.