It works great in Situation A):
Me: Jane, do NOT eat those lentils.
Jane: (giggling, shoves them into her mouth)
Me: Oh, you make me so mad. I said, DO NOT EAT THEM.
Jane: (rushing to eat as many as possible, still giggling)
Me: I AM NOT JOKING, JANE. I AM NOT TRYING TO TRICK YOU INTO EATING THEM. STOP IT RIGHT NOW.
Jane: (plate empty, giggling too hard to eat anyway)
Turns around to bite you in Situation B):
Me: Ow! Jane, don't hit me with that!
Jane: (giggling, wielding a plastic golf club)
Me: Hey! Seriously! That really hurts. Don't do it.
Jane: (wildly thrashing the club about, still giggling)
Me: (realizing the monster I've created, searching desperately for logic a two year old might understand) JANE! THIS ISN'T ONE OF THOSE TIMES WHEN I SAY ONE THING BUT WANT YOU TO DO SOMETHING ELSE. DO NOT HIT ME WITH THAT CLUB!
I blame Dennis Lee.
PS. PEI is way nice. You should visit.