I heard a pretty lady the other day refer to a barista as a barrister. Barista is Italian for bartender. Bartenders here and abroad mix and serve alcoholic and non-alcoholic beverages hot and cold. Entering English the word has suffered semantic shrinkage: a barista typically mixes coffee drinks only.

Baristas and barristers ply their trade in the vicinity of bars: standing behind them or before them, respectively. So the malapropism has a certain 'logic.'