This entire song is about the hit TV show “Gossip Girl” He is rapping from the point of view of 2 different character’s of the show about the main female character’s show, Serena and Blair. This is why the title of the song is “B.S”. His first verse is about Blair, rapping from the point of view of Chuck Bass but replaces his name with his nickname “Einstein”.
The second verse is about Serena from the point of view of Dan, another main character, but he does the same thing again and replaces his name with “Einstein”