Andy Lau and Siwon become close when they worked in the Hong Kong movie "A Battle of Wits" in 2006. Since then the Super Junior star has maintained ties with the famous actor. When Siwon's birthday came around, Andy Lau sent him a signed CD of his own album, Unforgettable. Siwon updated his weibo with a picture of the autographed album and the caption, "Teacher gave me this for my birthday. Aren’t you jealous?" Well, are you? (Source: