It is a Jewish practice to turn out your pockets on Friday afternoon before Shabbat and make sure that there is nothing there that is not Shabbesdik, not suitable to have around on Shabbat. The Talmud (Shabbat 12a) describes this as hilcheta rabati, a very important halachah of Shabbat.
In a neighbourhood without an eruv this requires turning out anything in one's pockets so as to avoid inadvertently carrying on Shabbat from one domain to another. In a place that does have an eruv it means getting rid of anything muktzeh, items that one should not move around on Shabbat such as money, pens or cellphones.
Rav Kook, the great 20th century mystic and halachist, adds that one should also empty out anything that, while not strictly forbidden to have around, is bound up in your mind with the toils, worries and frustrations of the working week (eg annoying letters or notes from meetings). Rabbi Kook explains that, on beginning Shabbat, we try to align our internal and outer worlds, and ensure that whatever is in our pockets does not jar with the inner peace that we aim to enter.