hi! i wanna preface my answer by saying my knowledge of bangtan lyrics is not great, so i'm not a trustworthy source here! but the main thing that comes to mind for me is his verse for yankie's song prometheus in 2015. (here's a lyric translation from @origamifirefly.) the lyrics "i'm a narcissist with perverted tendencies / i poke myself often / i kiss my own tightness" are pretty suggestive of some kind of anal play. also, later in his verse he says "ah oppa, i like it, please hit me a little more," which could be read either as a girl talking to him or as him talking to a male partner (oppa can have pretty sexual/pervy connotations, regardless of who uses it.) and this part is totally a guess/a question if anyone happens to have extensive knowledge of korean gay slang lol, but i know that the korean noun for "top" (in the gay sex way) comes from the verb to hit, and the word for bottom comes from "to get hit," so i wonder if the verb "to hit" can also be used like "to top"? which could make that read as "ah oppa, i like it, please top me a little more." i have literally NO evidence of that -- i did a quick google search to see if 때려줘, the word he uses for "hit me" in the lyrics, could be used as slang during sex and didn't find anything, and i also didn't find anything about hitting being used to refer to anything other than like spanking during sex in korean, but also most of the sources were talking about straight sex, so idk!