Why does my cat sit on everything I have in front of me?

Dump the cat and get a dog.

Because he's a pest.

Because he loves you and wants to be near you. Quite a compliment from a particularly independent animal. Be very proud of yourself, because he thinks your well worth it, and he is very particular.

He wants your attention. And some cats are worse than others about it. Give your cat the love he needs and deserves, and then set limits when he gets into your personal space. They're not stupid--saying NO loudly and putting your hand in the way should get the message across. If he keeps doing it you might want to put him in another room. I have a cat that loves to sit on my laptop and another that likes to block my view of the TV. They think they're more important than anything I could be doing.

If it fits, it sits.

He wants your full, total attention. Mine sits on my phone so I can't be on YA!

cause he thinks its fun to do that