Liff!

Those who are familiar with the admittedly limited works of one Douglas Adams will have probably fathomed a guess at what it is I would be attempting in this thread.

Liff:
(n.) A common object or experience for which no word yet exists.

http://liff.hivemind.net

Certainly there are "many hundreds of common experiences, feelings, situations and even objects which we all know and recognize, but for which no words exist," and I propose that we expand upon this list using a combination of modern ineffability and words that for better or worse "spend their time doing nothing but loafing about on signposts pointing at places."

Here's two to get us started:

• Malaga:
  (n.) In weight; the quantity of water held collectively by a man's beard and moustache after stepping out of the shower. In historic Scandinavia, one's malaga could garner greater respect among groups than one's ability in combat. Since showering was typically rare, however, there was less an opportunity to prove one's worth here than there was on the battlefield.
  
  
• Sayalonga:
  (n.) A modern dance imitating the movements of one who is trying to fumble his way quietly to the bathroom through an unfamiliar house at 2am.

Purranoia: The fear that your cat is up to something

Sounds a bit like Rich Hall's "Sniglets," of which my personal favorite is Sloopage (n.) - the tendency of a sandwich's contents to slip out from between the bread.

Again sticking to place name tradition, though it's not at all required:

• Chazey:
  (adj.) - The literal light-headedness one experiences after visiting the barber and having two to three years of growth lopped off in an afternoon.
  
  
• Tinker's Green:
  (n.) - The one paint colour which every warehouse has and which nobody ever asks for, but which is close enough to your desired colour that it might be swapped around in the vain hope that you won't notice.

I always rather liked "fot" - meaning the sound made when puncturing the waxed paper/foil membrane sealing the top of a new jar of instant coffee, normally with the thin end of a teaspoon.

Linked inextricably with this is the memory of one moron who decided to try to make a loud fot with a huge jar of coffee that had been brought from England to a ski resort high in the French Alps. The pressure difference meant that the result was a fountain of coffee granules scattered all over the floor. The scene became even more comical when a water leak later that day resulted in a half-inch layer of cold weak coffee on the floor of the apartment.

Some further discussion here.

Esso-asso: the guy who takes shortcuts through nearby gas station instead of waiting at red light.

Quedoh: Reaching the head of a queue just in time to witness the counter closing ritual.

Sprankton:
(n.) A disease you get from chewing too much.

Sprankton:
(n.) A disease you get from chewing too much.

Sprankton:
(n.) A disease you get from chewing too much.