The Red Cross
The red cross is a symbol that can't be used at will. Use of it will be considered as a a violation of the Geneva Conventions, and will be treated harshly.
"The red cross emblem or similar designs are not general signs of ambulances, health care, first aid, the nursing or medical profession, or similar matters. Moreover, they are not signs to be used for commercial purposes, such as for advertising campaigns or on products."
You can definitely expect a takedown request if you attempt to do so.