deep throat

Short definition from Wiktionary

Verb

1. 1
   Alternative spelling of deep-throat.
2. 2
   To perform fellatio or irrumation so that the entire penis is inside the mouth; often penetrating into the oesophagus, requiring the suppression of the gag reflex.

Noun

1. 1
   A secret informant possessing valuable information, especially one who stays secret long after the incident in question is concluded.