Technical offset printing term referring to the tin object containing roller cleaner, with a plunger on it, that sits near the end of a Heidelberg press. You pick up a rag, chunka-chunk a few times on it, and the rag becomes soaked with cleaners. So-called because it makes a chunka-chunk sound.
'Hey Baz, clean the rollers will ya?'
'OK' (grabs a rag)
'Hey Tone, the chunka-chunk is empty, can ya get some more chunka-chunk fluid from the chunka-chunk shop?'