Administratium

In 1991, Thomas Kyle (the supposed discoverer of this element) was awarded an Ig Nobel Prize for physics, making him one of only three fictional people to have won the award.

[1] A spoof article was written by William DeBuvitz in 1988 and first appeared in print in the January 1989 issue of The Physics Teacher.

[2] It spread rapidly among university campuses and research centers; many versions surfaced, often customized to the contributor's situation.

A similar joke concerns Administrontium which was referenced in print in 1993.

In other words, the more time passes, the more massive "Bureaucratium" becomes; it only grows larger and more sluggish.