Vent your spleen.
[Idiom] VENT YOUR SPLEEN. - Unlock Powerful English Idioms for Expressing Emotions
Express anger or frustration.
To "vent your spleen" means to freely express one's anger or frustrations. Historically, the spleen was believed to be the source of bad temper, so venting it would be releasing those negative feelings, similar to letting steam escape to reduce pressure.
Example Sentences
He vented his spleen at the unfair decision.
He expressed his anger about the unfair decision.
Frustrated by the politics at work, Susan went home and vented her spleen to her partner.
Susan shared her frustrations about work politics with her partner at home.
During the meeting, he couldn't help but vent his spleen about the new policy that he felt was unjust.
During the meeting, he expressed his anger about the new policy he found unjust.