Sparkling wine that is not very good at all. Shampagne is usually very cheap, not only in quality, but also in price.
Roger: Hey, Dave! How was Betty's New Year's Eve party?
Dave: It was OK, but the SHAMpagne she served was AWFUL! I'll bet the vintage of that crap was last Wednesday!!
1)Champagne
2)Reference to SNL skit starring Christopher Walken - "The Continental". The character offers all the ladies that come to his door "A Glass of Shampawnya", or Champagne pronounced in a swavy, swinger type accent.