There's a door at work I regularly need to access. It used to be used for another purpose but now is just an extension of the work area. It's got a badge reader and simplex lock but I can't get badge access because I don't actually belong to that work area yet I'm there everyday anyway. However, someone wrote the simplex lock code on a sign in very small numbers for this exact purpose. Other simplex locks in the building use the default code you can find online. The whole building is secure so you'd never be able to walk up to these doors without proper credentials, they are mostly just there to keep out the curious or someone looking to borrow tools that they shouldnt.