A student at Washington State University who felt charitable last week posted on Twitter that she planned to donate to St. Jude Children's Research Hospital.
It seemed simple enough: She told followers she would give 25 cents for everyone who favorited her tweet and 50 cents for every retweet.
But the tweet went viral. It reached nearly 200,000 retweets and 450,000 favorites, pushing her pledge to more than $200,000.
Danni Messina, 19, told the Huffington Post that she was inspired by a friend who was spending Thanksgiving in a hospital. She said she thought about all the children who would be in a hospital, fighting for their lives, instead of celebrating the holidays at home.