Justin Timberlake keeps Marine Corps Ball promise

The singer-actor took Cpl. Kelsey De Santis to the Marine Corps Ball in Richmond, Va., on Saturday, an experience he's calling "one of the most moving evenings I've ever had."

Why was Timberlake at the ball? It all goes back to a couple of months ago when De Santis made a YouTube video inviting Timberlake, and he said yes.

The 30-year-old singer posted a photo, along with a blog post on his website about the ball, explaining how he was honored to be at the event. "I knew I would have an evening that I wouldn't forget," he wrote. "Something I could tell my friends about. What I didn't know was how moved I would be by the whole experience."

Timberlake described his date as "humble and honest," even calling her his hero. He added, "I have to tell you, it's not every day that I meet a 23-year-old girl and she's more worried about if I'm having fun or if I'm comfortable! It hit me all of a sudden that these were the type of people that look after us and our freedom... Humble, concerned for others before themselves... This was the type of person our Marine Corps was building. I was really blown away."

De Santis asked Timberlake to the ball after the entertainer encouraged his "Friends With Benefits" co-star Mila Kunis to accept a similar invitation a few months ago. His urging worked; Kunis will go to a separate Marine Corps Ball on Nov. 18 in Greenville, N.C.