Little tiny pocket near hip on cycling jersey?

[MontyVeda]

It's where I keep my wraps of cocaine. The cops never find it.

Nail on head... all those TDF riders need to keep their stash in a handy, yet concealed place

 

[threebikesmcginty]

Hummer key.

 

[Headgardener]

If there is a small hole near the top of the pocket on the inside then it might be for an ipod Nano or similar MP3 player.