1 - The post-coital "What are you thinking?" Until you asked that question, he was probably thinking about how great the sex was. Once you utter that phrase, however, he immediately begins thinking about the two kids and 3-car garage you want.
2 - "Where is our relationship going?" You have a right to ask this question. But only sometimes and only in certain situations. These situations do not include right after sex, before bed, after drinking too much or first thing in the morning.
3 - "Do you love me?" If he's said it, then you should know your answer. Same goes if he hasn't said it.
4 - "Am I fat?" Regardless of how he answers, he knows you're not going to believe him and ask a series of follow up questions. Instead, refer all fat questions to your girlfriends, who know instinctually how to assuage your insecurities.
5 - "How many times have you had sex?" The question you should ask is about his sexual health - you have a right to know about any STDs. But the specifics of his sexual history are private. And you'll rarely get the truth anyway. He doesn't want the number to be too low, or too high. So he'll lie.
6 - "Do you want to meet my parents?" Of course he doesn't want to meet them - they'll give him the hairy eyeball because he's sleeping with their daughter. It might be better to say, "My parents are meeting us for dinner Friday."
7 - "What should we do for Valentine's Day?" This one Hallmark holiday always scares the daylights out of men. Help the poor guy out. Just handle the plans yourself.
8 - "How much do you weigh?" Men are sensitive about their weight just like women are.