These days some airlines will not allow you on the flight if your clothing might be considered offensive. A lot of people worry about germs on planes because you are confined. Take some airborne or another type of preventative medicine like that if you have any health issues or ask your doctor if you need something stronger due to compromise immune system. Wear comfy shoes too...and try to stretch your legs if the flight is longer than an hour. Sitting still for a long time can cause problems.