From Longman Dictionary of Contemporary Englishloosen somebody’s tongueloosen somebody’s tongueTALK TO somebodyto make someone talk more than usual, especially about things they should not talk about → loosen
Examples from the Corpus
loosen somebody’s tongue• The wine loosened his tongue.loosen somebody’s tongueloosen somebody’s tongueinformalTALK TO somebody if something such as alcohol loosens your tongue, it makes you talk a lot The wine had certainly loosened her tongue. → tongue 