Yesterday evening my 3 year old dd threw a paddy because 'there weren't enough puddings to go round'.
There's 4 of us, I'd bought a choice of 2 puddings - 2 of us are intolerant of an ingredient in one, cheesecake, so I'd only bought 2 cheesecakes and 4 of the other, so there was enough for everyone to have whichever they wanted, if you follow me. DD however saw these and complained about there only being two cheesecakes, as there weren't 4 for everyone.
After I explained older DD and I couldn't eat that pudding, reassuring her twice we didn't want that one, she promptly told me "you're being a stupid mummy" and proceeded to wail about wanting a "tees ache". I put one in front of her and DH took the other one but she continued to strop for a bit about how there 'wasn't enough' until she finally realised no-one was paying attention and ate the blinking thing.
Then afterwards went we went to sit in the living room she solemnly told me "don't do that again mummy, that was naughty, you need 1,2,3,4" (pointing at each of us while counting to show me adequately how many people needed to be catered for) and went off to play. Nearly cried for laughing 
What 'terrible things' do you inadvertently do to your toddlers?