1. Literally, to occupy positions on both sides of a single street in order to sell something to people walking on either side. Our sales were doing OK, but it wasn't until I hired a second food truck and started working both sides of the street that things really took off.

2. To aid, support, or engage with both sides of some issue, situation, agenda, competition, etc. Usually used with the implication of doing so in a duplicitous manner to benefit one's own interests or agenda, though not always. She was accused of working both sides of the street, acting as a legal adviser for groups trying to legalize recreational cannabis while also serving on the board of several organizations that have tried to quash actions. Look, I've been working both sides of the street in Washington for years, negotiating the rather volatile divide between corporate and political interests very carefully.