Singer Wheesung, currently serving out his mandatory enlistment in the army, made a surprise appearance on the latest episode of MBC's new variety program, 'Real Men'.

The new show revolves around celebrities enlisting into the army and going through the military experience, narrated by Girls' Generation's Sunny and Seohyun.

Making his appearance in front of the cast members, he displayed his full military strength, making them learn the official military fight song. Despite being a fellow celebrity, he spared no leeway, showing them no mercy and severely training them - just like a real military trainer would.

"No matter what you were in civilian life, you're all the same in the military," he shouted. "No matter how you get treated, make sure you keep your promises and mark my words well."

Watch the program below, Wheesung appears at 28:20 in the second video.