Summarize the following:
It's never a good idea to seriously risk the health of your eyes in the name of getting convincing redness. Never put anything in your eyes that's likely to cause serious irritation, including intense chemical irritants like "mace" (pepper spray) and natural substances like hot pepper products. In sufficient quantities, these substances can cause permanent damage and even blindness. If you're using a method that involves rubbing the skin around the eyes to induce redness, be sure not to touch the naked eyeball itself. Even if you manage to avoid injuring it, this runs the risk of transferring bacteria from your hands to the eyeball, which can lead to infections (as noted in the section above.) This risk is amplified if you've just touched something with lots of bacteria on it (like a doorknob.) In addition, since your eyeballs are so delicate, touching them directly can sometimes cause physical injuries. Even the smallest scratches can be quite uncomfortable when they're on your eye, while more serious injuries (like an irritated cornea) can require medical attention. We've all heard it before — marijuana use causes comically red eyes. While this is true, it's not a good idea to smoke (or eat) marijuana products as a way of getting your eyes red. If you're creating the red eye effect for acting purposes, the cognitive impairment that can result from a marijuana high can make it difficult to give an appropriate, convincing performance. Additionally, marijuana intoxication is often punishable by law, with punishments ranging from minor to severe depending on the local jurisdiction.

Summary:
Don't use strong irritants like pepper, mace, etc. Don't irritate the eyeball directly. Don't consume marijuana specifically for red eyes.