Say what? - To break the ice

(1) to relax a tense or formal atmosphere or social situation; (2) to make a start on some endeavor.

The phrase came into general use, in sense (1), in English through Lord Byron's "Don Juan" (1823) in the lines:

And your cold people [the British] are beyond all price,
When once you've broken their confounded ice.

In these lines the ice in question is metaphorically that on a river or lake in early spring. To break the ice would be to allow boats to pass, marking the beginning of the season's activity after the winter freeze. In this way, this expression has been connected to the start of enterprise for about 400 years.