Your car keys have better range if you press them to your head, since your skull will act as an antenna. It sounds like some made up pseudoscience that would never work in practice or have a negligible effect, but it actually works.

Edit: idk if it's actually because your skull acts as an antenna, although that's what I've heard. I looked it up and it seems like it's your head acting as a reasonance chamber. Since your body is conductive, your head can bounce and amplify the radio signal.