Advert decals

So I remember in the ol days of gmod and css people would have addons that allow ads to be placed inside maps with out recompiling the map, basically you would use a tool and place it into a location and it would save the coordinates and place a designated decal there for a simple and easy way to have a small advert inside the server rather than inside the text box.

Was wondering if anyone knew the name or where this went to, or even if it is still available.

Spray?

No. I know what sprays are, these were decals specifically placed through some kind of addon/mod that allowed them to place an image in location of the coordinates selected. and than it would load it upon map change or something.