Wiktionary
let off steam
vb. (alternative form of blow off steam English)
Usage examples of "let off steam".
When she wanted to let off steam, she went big-game hunting in Kenya.
On a voyage they were confined to the ship of necessity, but they reasonably felt that they were owed a chance to let off steam as soon as they made landfall.
They were very inviting, these small square panels, if you wanted to let off steam.
Occasionally, somewhat childishly, I let off steam by registering as Sam Hall, the subject of a rowdy old ballad we often sang in the MFS.
No self-respecting man could get through the day without his battery of four-letter words to cope with the roughage of life and let off steam.