expression, godan verb (-su)
let one's hair down; relax and have fun
Used when someone unwinds and enjoys themselves freely after a period of work, stress, or restraint. Often implies a temporary escape from daily pressures.
週末は友達と温泉に行って、羽を伸ばした。
I went to a hot spring with friends over the weekend and let my hair down.
試験が終
Let's really let loose after the exams are over.