Each character has multiple fatalities that they can perform at the end of the match in Mortal Kombat 9 (2011 version) for the PS3 and Xbox 360.
This is the list of fatalities, and the babality and stage fatality for Reptile.
These can be unlocked and added to your moves list by performing them in either Arcade Mode or Versus Mode.
Check out these complete fatality guides for more finishing moves:
Fatalities and babalities for Mortal Kombat on Xbox 360
Fatalities and babalities for Mortal Kombat on PS3
Xbox 360
Acid Yak – Forward, Forward, Down, Up, A in sweeping distance
Tasty Meal – Back, Back, Forward, Down, RT in jumping distance (requires Reptile’s Classic costume from DLC to have access to this move)
Weight Loss – Down, Down, Forward, Back, X while in sweeping distance
Babality – Back, Forward, Back, Down, A in jumping distance
Stage Fatality – Forward, Down, Down, RT at close range
PS3
Acid Yak – Forward, Forward, Down, Up, X in sweeping distance
Tasty Meal – Back, Back, Forward, Down, R2 in jumping distance (requires Reptile’s Classic costume from DLC to have access to this move)
Weight Loss – Down, Down, Forward, Back, Square while in sweeping distance
Babality – Back, Forward, Back, Down, X in jumping distance
Stage Fatality – Forward, Down, Down, R2 at close range