littledetective:

Later, right. For all he knew, ‘later’ meant
   days from now.

Tearing his seething gaze from the thief,
   Conan began to tug and pinch at various
   pieces of clothing. He missed his jacket
   and jeans, even if the material wrapped
   around him now was strangely comfortable.
   He had assumed from the start that the suit
   was only for show, but he supposed now
   that it made sense — one couldn’t
   successfully snatch a jewel while wearing
   something constricting and annoying.

A twist at the hips, and he followed the flow of
   the cape that fell from his tiny shoulders. It
   was then that he noticed a lack of red sneakers,
   upper lip twitching in a scowl. Of course, he
   should have expected that much — ah, but his
   watch and belt were still attached to him.
   Good, at least he had something to work with
   if his ‘twin’ became too amused.

“It’s not like anyone else will see me like this,” he
   spat, “so I’ll avoid the smiling part.”

“Killjoy…”

Despite the comment, the thief had continued to smile as the other checked over the outfit he’d been changed into, looking it over himself now that the chibi actually had it on. He hadn’t been entirely joking on the ‘younger’ part earlier. The size reference had come from his own clothes he’d worn as a child, using nicer ones he’d worn to his father’s shows, so he’d had a feeling it might fit just as well on the detective. Nice to know that assumption panned out.

“Even if no one will see you, it’s not like you’d lose anything by smiling either. In fact…” A flick of the wrist and a familiar pair of glasses appeared in his hand.

“How about this: You let me take one picture with you, where you’re smiling, and I’ll give these back now. And no, no one will see the picture, in case you might wonder.”