• Singer Sulli attends Tory Burch Spring 2016 at Avery Fisher Hall at Lincoln Center for the Performing Arts on September 15, 2015 in New York City.

Singer Sulli attends Tory Burch Spring 2016 at Avery Fisher Hall at Lincoln Center for the Performing Arts on September 15, 2015 in New York City. (Photo : Getty Images/Cindy Ord)

Former f(x) member Sulli's recent social media activity has rubber certain netizens the wrong way. The actress/singer, whose real name is Choi Jin-ri, is being accused of being disrespectful towards another actor.

On Dec. 19, Monday, Sulli posted a photo from the premiere of the new crime-action film "Master" on Instagram. In the image, Sulli can be seen posing with actor Lee Sung Min, 48, and model Bae Jung Nam.

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However, it was not the picture that stirred up the controversy but the caption that she wrote along with it. In her caption, Sulli said that she had not met Lee and older brother Bae in a long time and noted that they were at the event to show their support for actor Kang Dong Won.

However, while she addressed Bae with his full name followed by the word "oppa," she referred to Lee with his first name before adding "ssi" at the end. The 22-year-old singer's casual tone towards a senior actor was criticized by many of her fans.

Netizens left comments to point out that even though "ssi" is an honorific suffix that is often used to show respect to someone, it was inappropriate to use the term for a veteran actor more than twice her age.

In the wake of the negative comments, Sulli fired back with a comment of her own. "It's just a nickname that I use. Don't react so sensitively! Haha." All Kpop quoted her as saying.

Meanwhile, fans continued to criticize her on the photo-sharing platform, claiming that her choice of words was wrong. They noted that no matter how close the relationship between Sulli and Lee is, using a nickname like that is disrespectful towards the actor as well as his wife and completely uncalled for.

Sulli grabbed headlines last month after she was rushed to the emergency room with a wrist injury. The actress/singer's hospitalization sparked rumors that she had attempted to commit suicide and netizens were quick to speculate that some of her SNS posts hinted at her unstable mentality

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