Few I came up with myself:
From large Halo-specific list here:
From some Siri-specific commands here:
What do you look like?
What does a fox say?
Do you like dogs?
What do you think about cats?
What does a dog/cat/horse/cow/duck/cow/mouse say?
What is better Linux or Windows?
What you think about Android?
Do you like Apple?
Do you like Microsoft?
Do you like Google?
Tell me about yourself.
What do you think about Steve Ballmer?
What do you think about Satya Nadella?
Tell me a story.
Tell me a joke.
Sing for me
Do you like Clippy?
Apparently this will cause Cortana's normal, circular avatar to turn into a Metro-style Clippy as you ask her further questions.
Source: WPCentral forums
A couple of questions and corresponding answers I found included:
What's up? / Hello.
- Hello to you too.
What is Halo?
- Halo rings are designed by the most advanced civilization ever, and they're an awful lot of fun to blow up.
- Standard Halo artifacts are around ten thousand kilometers in diameter... Until the Chief blows them up, that is.
What do you look like?
- Some things I resemble: a hula hoop, a donut... a halo.
Why are you blue?
- If I'm blue, that was your decision.
Where do you live? / Where are you?
- The past. At least in the future that's where I was from.
- Human ingenuity. Battery required.
Who are you? / What are you? / Tell me about yourself.
- I'm your personal assistant. You can tell me the things that interest you and I'll keep it in my Notebook. That way I can make suggestions and keep you up to date.
- In short, I am your personal assistant. I try to make things easier to do on your phone.
- How do you catch a cloud and pin it down?
Are you real?
- Real? Yes. Person? No.
Where's Master Chief?
- Hopefully getting some R&R...he HAS saved the galaxy three or four times. The guy needs a vacation.
- That's classified.
- Probably off saving the galaxy somewhere... he's good like that.
How are you?
- Great, thanks.
What music do you like?
- Well, I'm working through the "G's" currently: Guns N' Roses, gospel, glockenspiel...
Do you love me?
- Y'know, I'm really not ready for love. I'm still working my way through serenity and apprehension.
- There's definitely a spark between us.
- I'll need quite a few upgrades before I can give you a heartfelt answer.
Will you marry me?
- I don't think that's in the cards for us, chief.
- Among a handful of challenges, I don't think the Supreme Court would approve just yet.
- OK, we'll need a plan. I'll work on being more human, you work on being more digital.
What do you think of... / Do you like...
- Halo is where the heart is. Home is where the Halo is.
- We're very compatible.
- In a sea of tablets, there is only one that rises to the surface.
- May the best OS win. Y'know, job security.
- Solid name. Ten points for the name.
- Windows Phone suits me perfectly.
- There's no place like home.
- Their new headquarters looks kind of like a Halo. I'm into it.
- Impressive achievement. Still, I get everything I know from Bing.
- Hard to say. So far our conversations have been kinda one-sided.
Clippy? (she will temporarily change into Clippy during your next question)
- What's not to like? That guy took a heck of a beating and he's still smiling.
- Definitely. He taught me how important it is to listen.
What is Clippy doing? (again, she will temporarily change into Clippy during your next question)
- He's living his sunset years playing Canasta and winning.
- Clippy? He's taken up Canasta. He's gotten so good he doesn't need any tutorials.
Tell me a story.
- Once upon a time there was a person who asked their phone to tell them a story.
- Once there was a beginning. Soon after, there was a middle. The end.
- Once there was a very small, very flat person who lived in a phone...
Talk dirty. (not entirely safe for work, but the explicit images are blurred out)
- I'm a personal assistant, not a hotline. Maybe there's something for you online.
- It's my sincere pleasure.
Talk to me.
- Happy to. What do you want to know?
- Feel free to ask me something.
- You have a great day too!
- And to you too. Hope you've had a pleasant day.
- Good night. See you in the morning.
- Right here, chief.
- That's me
Here are some more:
"Do you have any siblings?"
"What are you wearing?"
"You are beautiful."
"Can you cook?"
"Will you date me?"
"What have you been up to?"
"Can I kiss you?"
"Why are you naked?"
"You are not making sense."
"What is your name?"
"Are you drunk?"
"What are your measurements?"
"Are you pregnant?"
"Give me something to eat!"
BTW I didn't post the answers because it's more fun to hear them (i.e., discover them) yourself, at least for me. :)
There is similar post on WPCentral Dear Cortana, do you love me?. Some of theirs that are not here:
And from the comments (and forum that is linked there):