How do I get my bestfriends sister to dress me up in girl clothes like panties bra and all that?

huh! why would you want to do that dude???

im not sure why you would want herr to do this you should put more detail if you gay and want to be a drag or something then just ask her for her help im sure she will do it for you now if your straight and your trying this stuff on for fun just start by hanging out with her sis and go like i wonder wats its like to have to wear makeup and bras and underwear and stuff does it hurt y do you have to put on makeup stuff like that and if your straight and this is a weird way of hitting on her i wish you the best of luck cuz i promise you besides the you gotta take your shirt off to put on the bra stuff it wont help any instead try inviting her to the beach or ssomething