It's pretty easy to hide a lapel mic behind the ear. However, it kind of depends on what kind of mic you're trying to hide and where your scene is taking place. Tell us that, and I might have a better answer for you.
Sorry for not giving more info to start with! The male actor is a skateboarder who is supposed to collapse onto the ground, give the camera a grin and recite a few lines. The problem I'm having is that he's shirtless. Maybe I could hook the mic behind his ear and tape it down his back? I guess I'll give that a try. I already attempted to hide mics among the grass and the audio is just too muffled. The actor has a deep voice and mumbles a bit, which doesn't help.