During the act of performing anal sex, the man pulls out, jizzes on the woman's back and then throws a tarantula onto the jizz. The jizz then dries causing the tarantula to get stuck to the woman's back. This is a good technique that can be used to break-up with or assassinate the person you are sleeping with.
Tina: "My back hurts really bad. Ralph gave me the sticky tarantula last night."