1001 WHYs at 2.5 year old

I wrote a post on 1001 whats stage when he turned 28 months old. I thought the 1001 whys would come later.

Boy, I was wrong again.

It's exactly 30 months he gradually "graduated" to 10000 whys, ya I think 1001 was underestimated, but the whats didn't end, they just add up.

Mommy, what's that sound? (Referring to the motorcycle vrooming sound)

Mommy, what it say? (Referring to the GPS narration)

Mommy, why is it pink? (Referring to the GPS direction)

Mommy, why is that broken? (Referring to some other stuffs on the GPS)

Mommy, what is daddy doing? (Referring to daddy winding down the windows for immigration check)

Mommy, stamp here? (Referring to the stamp on passport I told him, he wanted the officer to stamp on his hand instead, just like amusement park entrance stamp!)

Mommy, what is that colour? (Referring to any random car that he could see)

Mommy, what is daddy's car colour? (I told him 1000 times it's Gold, I swear! Yet he could still ask 10000 times)

But if you ask him back, as suggested by some experts, "What do you think?"

He'll reply "I DON'T KNOW" with his innocent face.

Now, I need to get some 1001 whys reference book, any recommendation?