.... Moose, Cheese, Sister ........
I don't remember the subject of the thread, some story about a moose I think, but a freeper (don't remember their name, either), commented that "a moose once bit my sister." Several people just thought it funny and it sort of just took on a life of its own and became part of the lexicon.
I don't know where the "cheese" comes in.
See the Lexicon of FreeRepublic: http://www.freerepublic.com/forum/a3a4bb8761eda.htm
Thanks, turns out this is something I once knew and somehow managed to forget ;>