It is actually "over and out." This is just used when using a radio communicator, such as a CB. Sometimes pilots or army soldiers use these as a ways to communicate. Over and out means the same thing as goodbye. People say "over" on the radio communicator to show that they are done speaking. Here is an example:
A: We need more support for the trips on the ground. Over B: We can't give you more support. You'll have to wait. Over A: Please send them right away. We are having great difficulty. Over. B: We'll do our best. Over and out.