i have had a few good ones
(from the movie madagascar, the two chimps who want to escape to fling poo)
my message was in a bad british accent "If you have any poo, fling it now, otherwise leave a message"
my personal fave was what i called "farm induced panadamonium" i got volunteers: my kids, my neighbor, her kids, my cousin etc.
and everyone did a syncronized "noise jam"
kid play crying like baby, one going " mommy, mommy!! " over and over
one bleating like goat, one mooing, one clucking, one meowing, one barking, one just going "AAAAHHHHH!!!!!!"
and over all that mess i holler "if you'd like to leave a message, please wait for the beeeepppp!!!!!!"
it was way funnier than you can descibe it, and lots of teller marketers just hung up, and it descibed my life to a hectic T.
my kids keep saying we need to do another like it
i also had one with garfield's voice saying leave a message or hand over the lasagna