mettre son grain de sel

to butt into a conversation

This expression means to intervene in a conversation or matter without being invited, usually with a negative connotation.

Elle met toujours son grain de sel dans nos discussions.

She always sticks her nose into our discussions.

From the Latin 'cum grano salis' (with a grain of salt), found in Pliny the Elder's Natural History. In Latin, 'salis' meant both salt and wit. The French expression appeared in a Walloon-to-French dictionary in 1823 and entered mainstream French dictionaries in the early 20th century.