Dictionary

loosen someone's tongue en · VERB

(idiomatic, informal) To cause one to speak more freely; to cause one to discuss a subject that would not usually be discussed.
- We relapsed into silence. Presently he laughed. “There’s something in this starlight that loosens one’s tongue. I’m an ass, and yet somehow I would like to tell you.” 1896, H[erbert] G[eorge] Wells, “Chapter 4”, in The Island of Doctor Moreau (Heinemann’s Colonial Library of Popular Fiction; 52), London: William Heinemann, →OCLC; republished as The Island of Doctor Moreau: A Possibility, New York, N.Y.: Stone & Kimball, 1896, →OCLC:
- Tommy had apparently been plied with ice cream and soda pop at the police station, to loosen his tongue. 2000, Michael Chabon, chapter 11, in The Amazing Adventures of Kavalier and Clay, New York: Random House, page 552:
- He made a long stay in the dining-room after dinner, and, I fear, took an unusual quantity of wine, but not enough to loosen his tongue: for when he came in and found me quietly occupied with my book, too busy to lift my head on his entrance, he merely murmured an expression of suppressed disapprobation […] 1848, Anne Brontë, chapter 24, in The Tenant of Wildfell Hall:
- He admired the dexterity with which their host directed the conversation. The five young men had various tastes and their tongues had been loosened. 1904–1907 (date written), James Joyce, “After the Race”, in Dubliners, London: Grant Richards, published June 1914, →OCLC, page 54:

Spelling	Features	Source
loosens someone's tongue	Number=Sing, Person=3, Tense=Pres	lexicographic
loosened someone's tongue	Tense=Past, VerbForm=Part	lexicographic
loosened someone's tongue	Tense=Past	lexicographic
loosening someone's tongue	Tense=Pres, VerbForm=Part	lexicographic

hu megoldja a nyelvét (to cause (someone) to be less cautious or more free in what they say)