A phrase from a popular story where a flute player practices too much and ends up hating the thing she loves. After being given a pickle that "gets rid of problems" she attempts to play for the king and her flute disappears. Meaning her problem became her flute. This concert happened to be on a Tuesday in the story. This is used to say do not lose the enjoyment of doing something by doing it too much.
Friend 1: I just can't seem to wanna play this game anymore, I just get too stressed and always wanna win.
Friend 2: Well, they always say 'if there's a pickle in your pocket it is probably tuesday'. You should probably just play for fun before it ruins your love for playing.
On the surface, the word seems similar to 'pickpocket,' but it has a whole different meaning. A pocket picker, similar to a 'prison princess,' is a person who hangs onto the pocket of stronger, more dominant prisoners, mostly referring to gay people. It can also be used to refer to someone who is so far up someone else's ass that you can see the hair in the back of their throat.
Male 1: Yo, you hear about Male 2? He started picking pockets. People are calling him a pocket picker.