über den Löffel barbieren

Etymology
From in the sense of “to rip off, defraud”, as also in,.

The phrase refers to a traditional barber's technique where the shaving of a person with sunken cheeks would be facilitated by pushing them out with a spoon. In the present idiom, the phrase typically merely serves to intensify the meaning of the verb without any direct semantic relation.

Verb

 * 1)  pull a fast one