You can get a pink eye if you are allergic to dust or pollen. Irritants like shampoos, bacterial infection, dirt and smoke may as well cause pink eye. Pink eye results from inflammation/irritation of the conjunctiva as well as the interior lining of the eyelids.
Like anything else, cross contamination. If someone with pink eye were to rub their eye and touch something and you touch it after them and then touch your eye chances are your eye would be the next one turning pink and itchy.
Pink eye is very contagious so if someone has it and rubs their eyes then shake your hand and you touch your eyes, you will get it. Anyone who has it needs to be sure to use their own set of towels, wash cloths, pillow cases, etc. Everyone in the household needs to be diligent about good hand washing. If a child has pink eye, they should not be allowed in school until the doctor approves their return.
a person gets pink eye when they my shake a persons hand that has it ,but they don't know that they've gotten it yet or when someone at the store try on some shades and put it back (they had the pink eye but didn't know it)then the other person comes right behind them and wear it!!~HOT MESS
pink eye is contagious so if you shake the hand of a person you has pink eye and has recently rubbed their eye and you rub your eyes after shaking the persons hand then you will to be infected with pink eye.
Keep in mind that pink eye is a bacteria. It can come from anywhere this doesn't just include individuals or things around you. This also includes animals. Though your cat may look like it is suffering from plain "allergies", or has a lot of sleep in their eye be sure to wash your hands after cleaning it or touching any area around that pet (where they slept, where they sit, lay, etc.) because they too can carry pink eye, and you can catch it just the same as if it were from an individual.