When my brother was 17 and in boot camp, he was allowed mail. I sent him photocopied porn pictures of his head on a woman getting plowed by a big black guy every week and all the fast food wrappers I had eaten from through the week to look like an entire meal, including the straw, lid, salt/pepper/ketchup packets with a review of each. His drill instructors made him open up each letter and show everybody. They said they would hire me straight in as an instructor.