It came from the Greeks. The Greeks had drinking parties called Symposium where the participants would eat, drink and debate while reclining on couches.

The Romans thought highly of Greek culture and adopted some of the customs.

The Roman versions of these parties were called comissatio and convivium and reached Rome by 3rd century BC

http://referenceworks.brillonline.com/entries/brill-s-new-pauly/comissatio-e303460