Loosen somebody’s tongue
Definition 1 of 1
Pro Tip 1/3Social Situations
Used when someone becomes more talkative in a relaxed social setting. 
At the party, it didn't take long to loosen Lisa's tongue.
Pro Tip 2/3Not Literal
The phrase isn't about physically loosening a tongue; it's a metaphor for easing speech. 
A warm cup of tea seemed to loosen the old man's tongue about his past.
Pro Tip 3/3Emotional Relief
Can suggest someone finds relief in sharing thoughts or emotions they've held back. 
Seeing a friendly face, his anxiety eased and the meeting loosened his tongue.