The Rolled-Up Poster is an item in Homestuck. John Egbert had it on his dresser in his bedroom before he decided to hang it up on the wall. It evidently came from his father as a gift for his thirteenth birthday. The poster was the third item to appear in John's Captchalogue and led to the Fake Arms being dropped when John decided he would need a Hammer and some Nails to hang the poster on the wall next to his Problem Sleuth one.
Once John combined his Hammer and Nails onto one Captchalogue card, he was able to use them on the poster to hang it on the wall. Doing this revealed it to be a "Little Monsters" poster, which John adored.