1. Sleep Deprivation
    There's a reason sleep deprivation is used as torture. It's extremely effective. It disrupts every mental and physical function. The whole system is thrown offline, and serious consequences occur.
  2. Potty Training
    Easily the most confusing and frustrating parenting duty as far what has to be done. There is no consensus on the one right way to do this. Teaching a tiny, underdeveloped human why and how to use a toilet and not just go whenever and wherever is a Herculean task. It sucks.
  3. Repeat, repeat, repeat
    For such a "smart" species, we sure need a lot of repetition before we learn something. "Cover your cough/sneeze." "Say please/thank you." "We don't bite/hit/kick." "Use your words to say what you want." "Don't look at the sun."
  4. Time
    Your time is no longer yours. At least for the next 18+ years. There are prison sentences less than that.
  5. Judgement
    Everyone's a critic about how you parent. In-laws, your own parents, other moms, pediatrician, teachers, neighbors, etc. I'm working on not being a part of this too by repeating Amy Poehler's quote, "Good for you. Not for me."