'maters
'maters were a long running joke back in the very earliest days of Daria fandom, approximately from 1998 to 2000. (The word is prononunced much like it is spelled, a dialect form of the word tomatoes.)
According to fan Yui Daoren, Daria fan Smoochy-Jane suggested that as a shipper, if people didn't like her Daria/Trent stories they should throw tomatoes at her. This led to Rey Fox throwing a tomato (in prose, of course) on the message board. Supposedly, Smoochy-Jane preferred the 'maters spelling because she didn't know how to spell tomatoes in plural form.
Daria fans would later imbue each form of 'mater with special abilities.
Examples
pink 'mater
Fans hit with a pink 'mater will have the urge to write about Daria and Trent as a couple.
white 'mater
This 'mater neutralizes the effects of other 'maters.
black 'mater
This 'mater gives those hit with it the urge to kill or maim a major character in their writing.
ChewAsha 'mater
This 'mater gives those hit with it a Wookie-like appearance with the grammar to match.
The Killing Frost
Like any in-joke, the use of 'maters slowly dwindled away, leaving only puzzled fans who might read 'mater references in the works of early fans such as Crazy Nutso.