Wish there were a sure way to know if someone had a sexually transmitted disease? Now you can catch people red-handed, or uh, red-penised. Three British teens proposed an idea that will rock the world of safe sex- condoms that change colors when exposed to various STDs! Depending on what venereal disease you had, the condom could turn purple, yellow, or green. This new condom could potentially reduce the amount of people getting sexually transmitted infections! This is the new condom that changes colors when exposed to STDs.