One Way To Do It
Assuming they're not willing to (which a lot of guys would be for a night), if they're like me and have long hair, ask if you can straiten it, if they say no, keep annoying them about it. This is much more likely to happen then getting them to dress like a girl, so we'll use this as a starting point. Now once that happens, compliment them on how long it is, and start running your hands through it for a bit while they do something else, like play a game or watch a movie, anything that can distract them. Once they are not paying attention, slowly start to braid it, or give them another girly style, that wouldn't use any hair gel or anything like that. When that's done, get your sister, friend, or any girl about your age, to come in, show them, and tell them it looks cute or something, and keep complimenting them on that, until the let you keep it. Next, get them to wear a headband, hair ribbon, something like that. Since you've been playing with their hair for the last hour or so, they shouldn't mind as much and you can give them any girly style you want, since they will likely just take it out before they leave anyway. If they don't have long hair, skip that step, but it is probably going to be harder to start on the next step. Wait a day or two, and start doing it again. This time, we are going to work on getting them in girls clothing. Make sure they aren't wearing an expensive shirt or anything, and do something to get it dirty. If your clumsy, you can easily just spill a drink on it without being to blatantly obvious. Tell them you'll watch it, and pass them a plain blouse, which they shouldn't mind wearing. Do this a few more times, with a couple days in between, and giving them gradually girlier blouses, until they are fine with wearing one. Now for panties, have them come over, as just something to eat or hang out, but then before they leave, convince them to spend the night. When you two wake up, start getting changed, bring up the fact they don't have a change in clothes, hand them a blouse (again, once they're fine with that) a pair of jeans or sweatpants, and a pair of panties. Bring up that it's underwear and no one will see it. Have them spend the night again, so they get comfortable wearing panties. This shouldn't take to long, as again, they are currently unseen. Repeat this again, but make sure all your pants are dirty. Keep insisting wearing dirty clothes is gross, and hand him a skirt. This is probably the hardest part for now, but bring up that he's already wearing a blouse and panties, and he should cave in. Make sure your parents can't cook anything for lunch, and go to McDonalds or some place. He will likely refuse, but if he's hungry enough he will go. Bring up the point he would look like a perv, because likely it's still somewhat obvious he's a guy, and convince him to let you put a little make-up, most likely eye-liner, to make him look a bit like a girl. Also get him a wig if he didn't have long hair. Hurry, take a picture. Don't show him. Say you're texting someone or something of that nature, and snap a pic with your phone. This way, you can show him sometime later, that he dressed like a girl and was successful in doing so. You also have blackmail if you need that to advance any further. But now, you should be able to ask questions along the lines of "Can I dress you like a girl again?" and he will likely at least wear the clothing and hair whenever you ask. Again, have him spend the night, this time, before he goes to bed, have him wear the clothes and hair. Tell him to put on leggings or something if you want him too. But now, you should easily be able to paint his nails while he's asleep, and if you get that accomplished, he'll likely be fine with wearing any other make-up and girly items you want him too, as he's already in a girly outfit.