let off steam

女性車両に対する賛否など、痴漢やその対策にまつわる問題が後を絶えません。

Japan struggles to overcome its groping problem

According to Akiyoshi Saito, who manages a mental health program and wrote a book about the subject, some men have a compulsion to grope. In an interview with Asahi Shimbun, he explained that his main goal is to prevent recidivism among men who have committed chikan crimes. Unlike the general image, these men are mostly university graduates with good jobs and families, and their preferred targets are what he describes as unassuming women. Groping is a power game. The excitement has less to do with sex than with letting off steam and getting away with something. They are addicted to groping.

一部抜粋

https://www.japantimes.co.jp/news/2018/03/17/national/media-national/japan-struggles-overcome-groping-problem/#.Wq2qhXCRWEc

let off steamを取り上げます。『ジーニアス英和辞典』（第五版，大修館）を引いたところ、「（過剰の）蒸気を排出する」、「こもった精力を発散させる;鬱憤を晴らす」と載っておりました。Oxford Dictionary of English (2th) には、 get rid of pent-up energy or strong emotionと定義されております。blow off steam やburn off steam 、work off steam とも表現するそうです。

以上から、欲の発散というような意味合いで用いられていると思います。(Gomez)