This article shows the simplest technique there is for making a shower cap out of a plastic bag.
Steps
Step 1. Look for a clean, medium-sized plastic bag
If you have short hair, you can use a smaller one.
Step 2. First, collect as much hair as possible by securing it with pliers, rubber bands or bobby pins
If you wear bangs, remember to secure this section with bobby pins or clips as well.
Step 3. Now, slip the plastic bag over your head like a normal shower cap
Point the handles towards your ears.
Step 4. Pick up the remaining part of the envelope and spread it across your forehead
Step 5. Twist the remaining part as much as possible
If you leave it loose, the envelope will open.