Repeated word for word from a post by Lawprof Eugene Volokh, just 'cause I think it's great:
A vulture is flying south for the winter, but this year he decides to take an airplane.
The morning of the flight, the vulture shows up to the airport, but knowing that airplane food wouldn't be right for him, he brings a dead armadillo to snack on.
"Do you want me to check that for you?," asks the ticket clerk.
"No need," the vulture says, "it's carrion."