The latest Facebook check-in of Zac Efron on Monday says he is in Ho Chi Minh City, an unannounced visit that has immediately surprised and mesmerized Vietnamese fans of the former teen idol.

The 28-year-old, who found fame in the Disney "High School Musical" franchise, spilled the beans about his trip with a black and white photo capturing himself via a restroom mirror, captioned “Raiden in Saigon.”

Besides wearing sunglasses, Efron also dons two Vietnamese conical hats at a time and a mask, costume pieces that are typical of the Southeast Asian country, as seen in the photo that garnered nearly 85,000 Facebook likes at the time of writing.

The U.S. actor and singer apparently compared himself to Raiden, one of the legendary characters in the Mortal Kombat fighting video game series by Midway Games, who also wears a similar conical hat.

Comments, mostly from Vietnamese users, were immediately showered on the viral photo, with fans expressing their surprise and wishing their idol a good trip.

But there is little information about the Ho Chi Minh City visit of Efron, who debuted in the Disney Channel original movie High School Musical in 2006 as Troy Bolton, a popular student and captain of a basketball team.

On November 23, Efron allegedly visited the southern province of Dong Thap with his girlfriend, Sami Miro, as a picture showing them posing with several Vietnamese fans surfaced on the Internet.

It is believed that the couple chose Vietnam as their next destination after touring Japan last month.

Vietnamese fans are now trying to catch their idol in the flesh in Ho Chi Minh City, but it does not seem an easy task, with the actor dressing himself as any other ordinary tourist.

The California-born Efron began acting professionally in the early 2000s, and became known as a teen idol after his lead roles in the High School Musical, the Warner Bros. series Summerland, and the 2007 film version of the Broadway musical Hairspray.