Blue duck, red duck, gray duck
LuaLaTeX, 220 211 characters
command:
lualatex -interaction nonstopmode

Not the shortest, but the fanciest. Based on @skillmon's solution

\RequirePackage{tikzducks}\newcount\b\let~\def~\0{red}~\1{orange}~\2{yellow}~\3{green}~\4{blue}~\5{cyan}~\6{violet}~\7{gray}\loop\b\uniformdeviate8\tikz\duck[body=\csname\the\b\endcsname]; \ifnum\b&lt;7\repeat\stop