There are plenty of good reasons to have a boyfriend. Sex. Opening pesky pickle jars. Um, sex. But let's not forget the added bonus of nipping into your guy's dresser drawers and claiming the loot inside for yourself. Read on to get the lowdown on which dude duds to "borrow" for your fall wardrobe. Lemondrop: Lookalike Couples

Jean Jacket: Next time your man has his back turned, nick his rugged denim jacket. With '90s grunge style rearing its head once again, a jean jacket makes for a nice layering piece that will toughen up your flirty floral sundresses and add a casual spin on your dressier pieces. Roll up the sleeves, add some retro "flair" buttons, or throw on a brooch to give the jacket some feminine mystique.

Button-Down Work Shirt: Is there anything better than lazing around in your man's oversize Oxford? If your fella is of the Big & Tall persuasion, turn his crisp button-down into a sassy shirtdress by adding a belt and heels; just make sure that there's no tell-tale pocket hovering over your waist.

If he's on the smaller side, roll up the shirt sleeves and try pairing it with a fitted black or gray pencil skirt. You can also pair the shirt with skinny jeans and pearls for a boyishly glam look. Lemondrop: Oversize Accessories—Livin' Large

Plaid Shirt: As mentioned before, '90s grunge is back, and Loverboy's worn plaid flannels are perfect for getting your Nirvana on. Go ultra-grunge in a flannel paired with distressed jeans, or embrace your inner Riot Grrrl by throwing a button-down over a black minidress or floral sundress worn with—what else—Doc Marten combat boots. Consult Alicia Silverstone's Aerosmith videos for further inspiration.

The Boyfriend Jacket: Here's where having a petite BF (or little brother enrolled in boarding school) comes in handy. Steal his blazer and use it as a cardigan alternative. The key is the fit—the jacket should be fitted and even a bit snug if possible, so have it tailored if you can.

Sweatshirt: Designers like Alexander Wang have been all about the jock rock look lately, so re-purpose the dingy sweatshirt that you don't want him wearing anyway for your own. Pair it with a sexy pair of curve-hugging skinny jeans and heels, or cut the neck and sleeves and toss it over a slinky mini-dress for a Jennifer Beals 2.0 look. Lemondrop: A Flowchart for Lying to Your Boyfriend

Old-Man Cardigan: Yes, apparently there is a benefit of dating a guy who dresses like Mr. Rogers. His oversize cardigan—especially in earthy autumnal colors like brown, forest green, charcoal gray or navy—can be worn over summer's sleeveless dresses to give them a fall-appropriate update. Just add tights and a belt to tie it all together.