Curb 1.2 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software lies within System Tools, more precisely System Optimization. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free software for Mac OS X was originally developed by Fruit Stand Software.
From the developer:
Curb is designed to facilitate emptying the trash from removable media such as USB Keys.
When files are deleted on removable media, it is stored in a special trash folder on the media. These files take up room, robbing your drive of free space. Ordinarily to remove these files the user must empty their own trash, which includes files you
You may want to check out more software for Mac, such as Fluid Mechanics Calculator, Build-a-lot 2 - Town of the Year or Old School, which might be related to Curb.