he thought about this for about eleven seconds one afternoon , while rosie 's mother was handing them photocopies of an article from a magazine that she had found which suggested that rosie should stand on her head for half an hour after sex ; and he mentioned these thoughts to rosie that night , and she laughed and told him that her mother was n't allowed in their bedroom anyway , and that she was n't going to be standing on her head after making love for anybody .