USE ONE'S LOAF BRIT.
Meaning of USE ONE'S LOAF BRIT. in English
use one's loaf Brit.
informal
use one's common sense. [prob. from loaf of bread , rhyming sl. for 'head'.]
→ loaf
Concise Oxford English vocab.
Сжатый оксфордский словарь английского языка.
2004