There are a range of sexual behavioural practices that some people can consider to be outside the norm. Some of these practices carry with them particular levels of risk in terms of contracting or passing on HIV and other STIs. These practices can include fisting, bondage and sadomasochism play, and scat play just to name a few, and if you are interested in engaging in these practices then you should also be aware of how they can be risky, what types of risk they can pose and how to reduce and/or eliminate the risks altogether.
For more information about these practices check out http://www.downandirty.org/