Mooncalf

In Chapter 7 of Great Expectations by Charles Dickens, the word mooncalf is used as a sharp insult by Pip's sister Mrs Joe Gargery.  In this context, the Victorian slang means congenital idiots, simpletons, or fools lacking any urgency or awareness. 

The word appears at the very end of the chapter when Mrs Joe returns home in a state of high excitement. She and uncle Pumblechook have just arranged for Pip to go to Satis house to play for the wealthy, eccentric Miss Havisham -- an opportunity they believe will secure Pip's financial future. 

When Mrs Joe returns, Pip and blacksmith Joe Gargery are sitting by the fire, having a deep, quiet conversation about Joe's childhood and his bond with Mrs Gargery.  Frustrated by their calm slow demeanour in contrast to her frantic ambition, she bursts out: "here I stand out talking to mere mooncalfs, with uncle Pumblechook waiting, and the mare catching cold at the door, and the boy grimed with crock and dirt from hair of his head to the sole of his foot!" 

In British dialect crock refers to soot, smut or black grime.  Together with dirt as a phrase it means thoroughly blackened with sootnand soil.