jouer de la harpe

To steal, to pickpocket.

Literally "to play the harp." A pun on harpe (“harp”), which is also slang for "finger," and harper (“slang, to steal”), as well as an allusion to the digital dexterity needed to pick pockets, compared to that of playing the harp. Compare English fiddle (“slang, to mess with; to fraudulently manipulate”) and obsolete finger (“to steal, purloin”).

To be in prison; incarcerated, behind bars.

See pincer de la guitare (“to be bored in prison”, literally “to pluck the guitar”).