i aint playin - The only word in the world that makes every creature run for

The only word in the world that makes every creature run for their lives, even if they're not sure why.

Dog: 'I aint playin!' (then runs away from the kid who just spilled milk.)

Cat: 'I aint playin!' (then hides under the couch.)

Baby: 'I aint playin!' (then cries for 10 minutes.)