This comic phylax scene, I found at a krater on display in the museum of Matera, or Greek Matheola. The term phylax, applied both to the actors and to the plays themselves, and, through a modern extension, to the vases that portray them. It is found in the writings of several ancient authors.
This parodic, comic or even farcical tradition encouraged by the freshness of a new figurative language developed as less codified than that of Athenian painters. From 440 BC on, these red-figured vases were produced in Magna Graecia, so also in southern Italy. You can find pictures of them in sets of Matheola and Lecce; all at my Flickr account.
I couldn't find out which scene has been presented. The information available said: 'Cratera a campana apulo a figure rosse. 360-340 BC. Pittore di Graz. Scena teatrale'.