 When Freddy Krueger is chasing Nancy and she runs up the stairs only  to find that its all "goo", what she steps in is actually unknown.  According to the DVD commentary, Wes Craven (qv) claims "It was  just oatmeal", Jacques Haitkin (qv) says, "I think it was pancake  batter," and Heather Langenkamp (qv) says, "It was something  rubbery." A definitive answer does not yet exist.