Perms and hair color. You can color hair that has been permed, but try to use a semi-permanent or 'no-ammonia' color instead of a normal permanent color (which uses ammonia and 20 volume peroxide). Have your hair permed first.
Mowing grass works best when the grass is dry, as grass tends to bend over from the weight of the rain, making it difficult to get a straight cut. It also clumps inside your mower cavity and on your lawn, which can lead to dead grass underneath the clumps if not raked promptly.
Mowing your grass in the rain can be miserable for you, and it may not do your grass any favors, either. While some commercial mowers, with their balloon tires and super fast, super sharp blades can handle the task, most residential lawn mowers aren't up to it. At best, you may end up with a badly cut lawn.