something that can be used to stick posters on walls.
not to be confused with play-dough.
Sally lived in a rental house so her parents got her poster putty to hang up her posters with. She promptly forgot about it and while cleaning her room put it with her play-dough. several months later Sally found the play-dough and poster putty. They were slightly different shades of blue, and Sally realized that one of them must be the missing poster putty. she then picked up one of the play-dough thinking it was the poster putty, and used it to hang up her new Taylor Swift poster.
THREE YEARS LATER THEY MOVE AWAY. SALLY IS STILL A TAYLOR SWIFT FAN ANT STILL HAS THE POSTER HANGING UP.
Mom-- Sally, you need to take down that poster.
Sally pulls down the poster. The three-year-old blue play-dough has left a huge blue stain on the wall.