To break the ice
= to create a relaxed atmosphere; to make a situation more comfortable
- Erin is so extroverted, she always can break the ice when I introduce her to new people.
- No one is talking, I hope someone breaks the ice soon!
Also: Icebreakers = (noun) games people play in groups of people to get to know them.
- The camp counselor played icebreakers with the new kids.
Sometimes the noun is divided into two words: Ice breakers.