Short answers, pulled from the story.
A drinking song is a song sung before or during alcohol consumption. Most drinking songs are folk songs or commercium songs, and they vary from person to person and region to region in both lyrics and melody.
In Germany, drinking songs are called Trinklieder. In Sweden they are called dryckesvisor or snapsvisor, and they are associated with specific celebrations including Christmas and Midsummer.
"Helan går" is a well-known Swedish drinking song associated with Midsummer and other celebrations.
Franz Schubert wrote at least eleven numbered drinking song lieder (Trinklieder), spanning from D 75 in 1813 to D 888 in 1826. One piece, catalogued as D 426 from 1816, has been lost.
"Libiamo ne' lieti calici" appears in Giuseppe Verdi's opera La Traviata. It is performed as a party scene duet and is one of the most recognized operatic drinking songs.
"Asturias, patria querida" is both the official anthem of Asturias and is commonly depicted as a drinking song.