"Picard" singing a drinking song
A drinking song was a song that was usually sung during the consumption of alcoholic beverages. Klingons were fond of drinking songs.
"Heart of Oak" was one such song. In 2366, a replica of Jean-Luc Picard sang it with members of USS Enterprise-D's crew, something which caused William T. Riker to question what his "captain" was up to. (TNG: "Allegiance")
"Auprès de ma Blonde" was a traditional French language drinking song. In 2367, Jean-Luc Picard and his brother Robert sung it while drunk after having fought and then reconciled. (TNG: "Family")