Francophonie· medium· informal
en avoir gros sur la patate
“to have a lot sitting on the potato”
Meaning
To feel very down about something
Explanation
'Patate' is slang for the heart here, so having it 'gros sur la patate' means carrying some real hurt or disappointment.
Example
Depuis qu'elle a perdu son emploi, elle en a gros sur la patate.
Ever since she lost her job, she's been feeling really down.
Origin
It shows up as early as 1919, in Gaston Esnault's dictionary of WWI soldiers' slang. It's really just a folksier version of 'en avoir gros sur le cœur', with 'patate' standing in for the heart.
Source