go pear-shaped
US /ɡoʊ pɛər-ʃeɪpt/
UK /ɡoʊ pɛər-ʃeɪpt/

1.
mal tourner, partir en vrille
if a plan or situation goes pear-shaped, it goes wrong
:
•
Our plans for the picnic went pear-shaped when it started to rain heavily.
Nos plans pour le pique-nique ont mal tourné quand il a commencé à pleuvoir abondamment.
•
The whole project went pear-shaped because of poor management.
Tout le projet a mal tourné à cause d'une mauvaise gestion.