The 26-year-old singer curled her hair, drew on dark eyebrows and applied lashings of red lipstick as she posed for a picture on her micro-blogging site Twitter, reported Sun online.
"Happy Birthday Marilyn. They'll never take our blonde hair and lipstick," she posted.
Gaga has now become the official Queen of Twitter after becoming the first person in the world to have 25 million followers.