The listing, Goosebumps Monster Blood by R.L. Stine has ended.
MONSTER BLOOD is about a twelve year-old boy named Evan Ross who is forced to spend a few weeks with his deaf great aunt. Evan's father is being transferred to Atlanta, Georgia and the only person who can watch Evan while his parents are househunting is great aunt Kathryn. One day while on a visit to an old toy store with his new found friend, Andy, Evan buys a can of stuff called "Monster Blood". Evan doesn't think much of it and he and Andy spend the afternoon playing with the green silly putty-type substance. However, as time goes on the monster blood begins to grow and starts to act like its alive.