That One Word You Can't Spell

Every Friday, I post a series of unrelated questions meant to spark conversation in the comments. Answer one, answer all, respond to someone else's reply, whatever you want. Very casual. On to this week's topics of discussion...
1. By all indications—her general grasp of most issues, standardized test scores, the sheer number of books she's read, the valedictorian plaque in our storage closet—my wife is a brilliant woman. But the other day, she had to ask me how to spell "occasion."
"That's the one common word I can never spell," she said.
For me, it's humongous. (It just took me three tries.) What's that one word you can't spell?
2. This next question comes from reader Mark of Tennessee:
"I run a small tutoring company and recently put the finishing touches on a home office in my basement. It's just so boring! Do you have any ideas for fun items I could display? I've got two bookcases, a couple empty shelves and plenty of wall space to work with. Help!"
I'll ask it this way and hope one of your answers inspires Mark -- what's the most interesting thing you've got on display in your work space?
3. If you had to pick one board game to play against a stranger with $15,000 on the line, which game would you choose?
4. I really enjoyed yesterday's article on unique special collections at university libraries. Let's pretend you've been hired by your local library to curate a new special collection of your choice. What subject would you collect (and become the world's foremost expert on)?
[See all the previous Friday Happy Hour transcripts.]