what is deep throat?
Second episode of the first season of "The X-Files".
Deep Throat (The X-Files episode)
Deep Throat" is the second episode of the first season of the American science fiction television series "The X-Files", which premiered on the Fox network on September 17, 1993. 
wiki:21892891
Deep Throat (The X-Files episode) [SEP] Introduction
Undeterred, Mulder continues and comes closer to the truth about extraterrestrial life than ever before, only to have his progress taken away from him again. The episode introduced the Deep Throat character, played by Jerry Hardin, who served as Mulder's informant for the first season. The character was inspired by the historical Deep Throat, and served to bridge the gap between the protagonists and the conspirators they would investigate. The episode itself focused on common elements of ufology, with a setting reminiscent of Area 51 and Nellis Air Force Base. It contained several special effects that Carter later described as "good, given the [series'] restrictions"; although he singled out the scenes featuring blinking lights as being poorly executed.