What is a 187 creature (aka CIP)?
A 187 creature is one that has a coming into play effect that, generally, blows up a permanent. Some examples of this might be a Nekrataal, Uktabi Orangutan or a Knight of the Mists. These are so called because 187 is supposedly a police code for homicide. CIP is an ancronym for Coming Into Play, hence a 187 creature is also a creature with a CIP effect.