les doigts dans le nez

very easily

This expression means to do something effortlessly, with one hand free, so easy you could do it with a finger up your nose.

Elle a réussi l'examen les doigts dans le nez.

She passed the exam with no trouble at all.

First documented in the 1910s in horse racing commentary. A jockey who won so easily he didn't even need to hold the reins could, in theory, put his fingers in his nose. The image stuck and spread to everyday French.