1. mouthfuck - Noun
2. mouthfuck - Verb
mouthfuck (plural mouthfucks)
(vulgar, slang) An act of aggressive, vigorous fellatio; irrumation.
(vulgar, slang) To aggressively and vigorously penetrate a mouth and throat; to practice irrumatio.
(vulgar) To scold someone harshly.
Source: en.wiktionary.org