If a woman sees a snake staring at her, and she wants to find out if he loves her or not, she should throw her clothes at the snake. If the snake ignores her clothes then it's nothing, but if he wraps himself around her clothes then he loves her (Shabbos 110a).
What should she do to get rid of the snake? She should have sex (with her husband) in front of the snake (To turn off the snake). Some say that it's just the opposite; he will get turned on even more! (See Rashi, Berayshis, beginning of chapter 3) Rather, she should take some of her hair and nails and throw them at the snake, and say "I am menstruous". (ibid)
The bottom line is that if you want to test someone if he/she loves you (sexually), you put your clothes in a room with a video camera, and you see: if the other guy will ignore your clothes then forget it. But if he/she loves you and he knows it's your clothes, he will smell it and fiddle with it, and maybe even hug it. (Click Jul 10, 12)