lasciarsi andare

Italian

Literally, “let oneself go”.

lasciàr si andare (first-person singular present mi làscio andare, first-person singular past historic mi lasciài andare, past participle lasciàto andare)

to let oneself go (both senses)
- 2012, John Green, translated by Giorgia Grilli, Colpa delle Stelle [The Fault in our Stars], Mondadori, page 57:
  Stava finalmente cominciando a lasciarsi andare all'entusiasmo, e si è messa a prendere appunti sul telefono...
  Finally, she started to get excited, typing tasks into her phone...
  (literally, “She was finally starting to let herself go with enthusiasm, and she started taking notes on the phone...”)
to let one's hair down