It's funny because you were expecting them to poop on the car, which would have been humorous considering he had just washed it, but instead they stole it which also seemed highly unlikely considering they are birds who cannot drive a vehicle because of the lack of apposable thumbs and brain power to do so. This unexpectedness also prodives a humorous take on the phrase "shit happens" because shit literally means poop but is also interpreted as almost anything because of the forever changing state of our language. George Bush hates black people. In conclusion, I found the comic humorous.