[let off steam] or [blow off steam] {v. phr.}
1. To let or make steam escape; send out steam.
* /The janitor let off some steam because the pressure was too high./
2. {informal} To get rid of physical energy or strong feeling through activity; talk or be very active physically after forced quiet.
* /After the long ride on the bus, the children let off steam with a race to the lake./* /When the rain stopped, the boys let off steam with a ball game./* /Bill's mother was very angry when he was late in coming home, and let off steam by walking around and around./* /Bill had to take his foreman's rough criticisms all day and he would blow off steam at home by scolding the children./
Compare: BLOW ONE'S TOP, LET GO(6).