"Melm" -- that is, the word itself -- is a monosyllabic expression of...well, just about anything. It's one of a long series of unintelligible neologisms that characterize the conversation of a small, bizarre group of people. This particular melmism was first uttered many years ago by Grand High Melm Chris Manly. Since that time, your humble sitemaster, Uncle Mikey, has been trying to spread the Gospel of Melm to the far curves of the Internet.(The astute may have noticed my sig tag on blogger is /vm. It stands for Very Melm. That's me. If you ask Uncle Mikey (he's my Uncle Mikey, he's your Uncle Mikey, he's even a real Uncle Mikey now, but he's always been everybody's Uncle Mikey), he'll likely explain why (he might even also tell you about Rargh). You may not understand the answer, but you'll pr'bly get one.
Melm -- the concept -- is sort of like Zen, only...well, stranger. Some might even say that, by comparison with Melm, Zen is comprehensible and straightforward a concept. Melm shares with Zen (and with the Matrix) the quality that it is very difficult to define. One knows Melm when one sees Melm.
Drew "Bob the Dancing Monkey" Johnson, the Mad, Mad Minnesota Melm, offers this expansion on the theme:
Melm is the sound of a stock option turning into a mushroom. The smell of Silent Bob pontificating about the beautiful blonde chick that Gary Gygax has no chance of getting into bed. It is Kate Bush's lips used as a croquet mallet in a large-scale recreation of the Battle of Waterloo starring Alicia Silverstone and the schoolmarm from 'Little House on the Prairie', the one you always get mixed up with Daisy Duke's halter-top (the schoolmarm, not her blouse).
Melm - the one-sided, double-minded Penguin Mint with the reflection of a thousand laughing Greys on the beach party of the Green Knight.