My son wanted to see colorful letters. This is what I came up with. He actually stayed awake as I type it. It was originally a one liner done in IRB.

letters.rb

az=("A".."z").to_a.map {|m|
  "\033[38;5;#{rand(180)+16}m#{m}\033[0m" # wrap char in random color
}
loop {
  puts [az*" "] * 25 # fill some of the screen
  az<<(az.shift)     # rotate chars
  sleep(0.3)         # slow down
  puts "\e[26F"      # cursor up 26 lines
}