Fun:Unobtainium

From RationalWiki

Unobtainium is the reason why you need those m billion^[1] dollar grants for your brand new supercollider.

Unobtainium will provide cheap energy, fuel faster-than-light travel, and whiten your teeth while you sleep. Sadly, it also has a half life of 15 picoseconds.

[edit] References and notes

1. ↑ They aren't that cheap any more...