A flag because it shows where or what you are representing.
This is probably a joke but I'll answer anyway
By 'cheeks' they mean buttocks so by "making them clap" is referring to them being so big/thick that they clap or make noise when you walk or move around or something.
I probably got played lol but whatever
I dont know if this will help, but He Played The Organ, Harpsichord and the Violin.. I hope this will help a bit. Good Luck!