Song Seung Heon has done it at least four times, Lee Min Ho a minimum of three times, Choi Si Won twice and Kim Soo Hyun, Lee Seung Gi, Choi Jin Hyuk and Lee Dong Wook all at least once. Kwon Sang Woo is another repeat offender.
These good-looking Korean actors are guilty of taking off their shirts to sell the dramas they appear in.
Men showing skin in K-dramas is so common that Choi Si Won, in a 2011 episode of variety show Strong Heart, said he was surprised at not being asked to do so in espionage drama Athena: Goddess Of War (2010-2011). He is known to flaunt his six-pack abs on stage as a member of boyband Super Junior and also did so in the dramas Oh! My Lady (2010) and The King Of Dramas (2012).
Sure, selling sex appeal to boost ratings is one of the oldest tricks in a television producer's books, but the unusual thing in South Korea is that the actresses are left out of the equation. Compared with their male co-stars, they remain relatively covered up in K-dramas, even in bed scenes. The reverse sexism occurs because Koreans like their women to be demure and conservative.
Media studies lecturer Tan Li Yi, who is married to a Korean information technology manager, observes that K-dramas depict everyday life in South Korea and reflect how women are supposed to behave and dress in society.
According to Ms Kelly Yu, 38, a Korean mother of two living in Singapore, women in South Korea do not wear revealing tops or dresses, not even during the hotter summer months. If they do, people might stare and some senior citizens might even go up to these women to scold them.
It was only after Ms Yu moved to Singapore about 14 years ago that she wore her first spaghetti-strap top. She also notes that even K-pop girl groups have to sell sex in a covert way by showing off their legs rather than cleavage.
Radio DJ Lee Xin Ying, 29, who used to host a K-pop radio show and Web television programme, says producers of these dramas, which are usually aired during prime-time from 8 to 11pm in South Korea, probably take into account the fact that children and their grandparents could be watching the shows.
Ms Lee, who now hosts the entertainment news segment on UFM 100.3, says: "While some might object to seeing a woman take her top off, most are okay with a man without his shirt on screen. That's why the responsibility to heat things up on screen falls on the actors' shoulders."
And how the Korean hunks have been manning up to the task. For actor Song Seung Heon, 37, from as early as 2003 in Summer Scent, pondering a dilemma or getting all angst-ridden over an emotional problem is not complete without him doing it topless and in the shower. Including Summer Scent, he has stripped in no fewer than four shows, including East Of Eden (2008), My Princess (2011) and When A Man Falls In Love (2013).
Lee Min Ho is catching up.
When retail sales assistant Siti Noraisyah, 26, saw him in the 2010 drama Personal Taste wearing nothing but a towel in one scene, she immediately grabbed her mobile phone to text her friend: "His body is to die for!" She proceeded to capture the image and save it in her laptop for keepsakes.
Lee went on to do the screen striptease in two subsequent dramas, City Hunter (2011) and The Inheritors (2013).
K-drama fans have compiled and posted online lists such as Top 10 K-drama Shower Scenes and The 8 Types Of Steamy K-drama Shower Scenes.
Lecturer Ms Tan, a former radio DJ and author of two Korean travel books, says these scenes boost ratings. "When a hot, up-and-coming actor strips in a drama, it becomes a talking point among his fans. This helps in the publicity of the drama."
Indeed, administrative clerk Sharon Tan, 28, says her idol Lee Seung Gi recently set tongues wagging among fans like her when he took off his shirt in the new police drama You're Surrounded. In the show's first episode, the actor-singer is changing in the men's locker room when the female lead, played by Go Ara, accidentally opens the door.
Ms Tan says: "It was the first time we got a frontal view of his upper body. In his previous dramas, they were only fleeting shots. The camera even lingered on him for a few seconds. My friends and I were surprised by the scene because he seldom strips, not even during his concerts."
She tells Life! she thinks Lee looks "lean and tanned" and "his abs are quite defined", which is appropriate for his role as a policeman on the show.
She adds: "I think he's trying to show a different side of himself in this drama. He is known for his boyish image in dramas such as Brilliant Legacy and My Girlfriend Is A Nine-Tailed Fox. Now, he is taking on more manly and mature roles."
Dr Doobo Shim, media and communication professor at South Korea's Sungshin University, attributes the male-striptease-on-TV phenomenon to the fact that these dramas are targeted at women and written by women.
Many television drama writers in the country are women, including Hong Jung Eun and Hong Mi Ran, also known as the Hong Sisters who penned You're Beautiful (2009), My Girlfriend Is A Nine-Tailed Fox (2010) and The Greatest Love (2011); Kim Eun Sook (Secret Garden, 2010, and The Inheritors, 2013); and Lee Kyung Hee (I'm Sorry, I Love You, 2004, and The Innocent Man, 2012).
Dr Shim says these scenes could have been written as "fan service". The term, which originates from Japanese anime and manga fandom, refers to material intentionally added to please the audience. He adds: "Being women, the writers not only sense female viewers' desires, but they also have the power to insert those scenes. It goes without saying that their own desires are reflected."
Ms Siti appreciates the gesture. She says she never tires of seeing her idol Lee Min Ho's body on screen. She says: "Unlike other singers, he doesn't take off his shirt during fan meets. Some of these dramas are the only way fans get to see his body."