1. What among hackers is called a
display hack. Classical effects include plasma
(colorful
mess), keftales
(x*x+y*y
and other similar patterns, usually combined with color-cycling), realtime
fractals, realtime 3d graphics, etc. Historically, demo effects have
cheated as much as possible to gain more speed and more complexity, using
low-precision math and masses of assembler code and building animation
realtime are three common tricks, but use of special hardware to fake
effects is a Good Thing on the demoscene (though
this is becoming less common as platforms like the Amiga fade
away).
2. [Finland] Opposite of dancing frog. The crash that happens when you demonstrate a perfectly good prototype to a client. Plagues most often CS students and small businesses, but there is a well-known case involving Bill Gates demonstrating a brand new version of a major operating system.