This is information gathered from other internet sites and what was gathered from chatting with people online through MSN, Twitter and Skype.
Bio-Hazard Tattoo - Color: Black
This is a picture of a man with the biohazard symbol tattooed on his right shoulder.
In some GLBT community circles, an equivalent tattoo is a convenient, perhaps aggressive way of announcing one has HIV. I've even seen it down here in the Deep South, on an HIV+ friend of mine, at the base of his neck.
Information Source: http://www.streetprophets.com/story/2007/4/13/31847/2104
Bio-Hazard Tattoo - Color: Red

This bio-hazard image in the color red. I was told different answers from several guys. However if you want to know for sure you will have to do your own research. This information I have gotten is from guys I have twittered with online, plus chatted with on MSN and Skype. Also, these guys have the black and red bio-hazard tattoos.
Here are two unofficial statements that were said:
- it means HIV positive and only engage in unprotected sex
- it means HIV positive and will only have sex with other HIV positive guys. Another word for that is called "Sero-Sorting".
Tattoos: A journey of HIV acceptance
To read more information about it and to watch a video about it, click the hyperlink below.
Information Source: http://www.cnn.com/2011/HEALTH/08/10/hiv.tattoos/index.html