Why ask Why?

About a month ago, "Why?" entered into Megan's vernacular. At the time we noted it as a mildly interesting development at best. But now, we're thinking it is just about the most annoying thing ever, as our nearly every statement is followed by a probing "Why?"

For instance, last night one of Megan's songs sparked an idea in Megan for dessert. The conversation might not have been all that nerve-wrenching if we hadn't had at least a dozen similar conversations earlier in the day.
M: Can I have brownies for dessert?
P: No, Meggie, we don't have any.
M: Why?
P: We didn't buy any at the grocery store.
M: Why?
P: I guess we forgot. (This seemed easier than telling her we don't want her to eat lots of sugar. She seemed to buy it because she didn't respond with a 'why').
M: Can we go to the gross-ry store and buy some?
P: No, honey, it's too late.
M: why?
In my head, I am contemplating shouting,"Because the earth's daily rotation has moved us to a point that is hidden from the sun, which causes it to be dark, and as the hours of darkness tick by, the day becomes late. NOW DON"T FRICKIN' ASK ME WHY AGAIN!" but instead I just say,"Because it is almost bedtime." For a split second I brace myself for another "why?" but Megan thankfully is ready to move on.


Megan is also liberally using, "usually," "belongs," and "nevermind" these days. And by liberally, I mean way too much. The former two Megan uses in a really parental way, which I don't really like, because I am the parent!
"We usually don't stand on chairs." and "We usually don't stand on the bed." Megan informed me, when I just so happened to be standing in said places. "Liam usually likes peas," she told me, as I was trying to get Liam to eat squash. "Shoes don't belong on the desk" she said, as she saw my shoes right at her eye level.

"Nevermind" Megan has decided is a perfect synonym for 'no' and so is still a bit awkward from her.
P: Do you want some more milk?
M: Nevermind.

P: Do you want to kiss Liam goodnight?
M: No. Nevermind.

I guess I should ask her Why?