A German, an Irish, and a Polish were being chased by the police with dogs.
They had been running forever and knew that they couldnt keep it up all night, so they decided to try and hide. The German fellow climbs up a tree as the other two run on and wait. Soon the police comes, their dogs barking like crazy. The dogs run up to the tree containing the German and start barking. The German panics for a second, then goes "Chirp chirp chirp".
"Aww, its just a bird!" the police say and keep going. Seeing that it worked, the Irish climbs another tree as the Polish guy keeps running. When the dogs start barking at the tree containing the Irish guy, he remembers what the German guy did and goes "Whoo... Whooo..."
"Awww, its just an owl. Lets go!" so they keep going. Now the polish guy sees that it worked twice already, so hes really relaxed in the tree hes hiding in. When the dogs come and start barking like crazy at his tree, he goes "MOOOOOOOO..."