Wait in your sister's bedroom

Right now in your current outfit, you realize you would attract a whole lot more attention than you're willing to deal with. You approach your sister's bedroom, knock on her door and hope for an answer, but nothing happens. You open the door to confirm your assumption, and she's truly not at home right now. Right when you needed her most, damn it! For better or worse, this gives you the chance to snoop around a little bit and get a better idea of what your life will involve for the next few days.

You open the door and only reluctantly have a look around in her room, given how you would usually fight tooth and nails for the priviledge of staying out of there. For now it was your best chance at 'blending in'. Your sister has a little corner set up with a tall mirror and an assortment of make-up. Along the wall was a wardrobe at least twice the size of your own, but then again, you never really cared much for a good selection of clothes. Men usually don't have to try and look pretty.

"Gwen!?" you shout to make sure your sister wasn't just roaming the house, but your call goes unanswered. You finally decide to open the wardrobe, and get overwhelmed by a massive selection of clothes! It's like she stored a whole shopping mall in there or something...
You quickly pick a couple subtle pieces in a nicely neutral, dark color and toss them backwards onto Gwen's bed. It didn't take long for you to finish two sets, and you return to the bedside to inspect the outfits a little closer.

The first set consisted of yoga pants, a sports bra to keep the added weight on your chest in check, and a tank top. They were typical gym clothes and you doubt you would get a whole lot of attention, negative or positive. To go along with the outfit you picked a dark thong - not like it was by choice. Apparently your sister only owns underwear that highlights the feminine charms. She obviously didn't get cursed with super fertility like you did...
Good thing you got no interest in getting laid for the next 48 hours regardless of what happens, within no time you'll be back to playing soccer and brawling with the buddies.

The next collection was pretty much just a mix of different things you could find. A checkered short skirt, stockings, a white shirt and a jeans vest. You furrow your brow at the thought of wearing that stuff, but it did look more fitting than your currently oversized men's clothes. The less you stand out from a crowd, the better. As you take a closer look at the underwear and try to untangle the mix of strings, you get the impression that the crotch piece is... missing? You shake your head and decide to take a better look later.