Biohazard is a shorthand term for "biological hazard". It refers to biological substances that pose a threat to (primarily) human beings. This can include medical waste, samples of a virus or bacterium that can affect humans, and so forth. It is generally used as a warning, so that those potentially exposed to the substances will know to take precautions.

Alloilux > Caisius ...let it be, i didnt talk with Gay people like you .
Caisius julius > you are one to talk with that avater
Caisius julius > just saying