A Hink Pink is a riddle that has an answer composed of two one-syllable words that rhyme. For example:
What’s an overweight feline?  (The answer: Fat Cat)

There are also Hinky Pinky riddles (with answers that are two two-syllable words) and Hinkety Pinkety riddles (with answers that are two three-syllable words.) Here are examples:

No need to stop there. A riddle could be a mixture, for example a Hinky Pinkety: What’s a little yellow bird that badly needs to see a barber?  (The answer: hairy canary)

Or it could be a Hinky Pinky Rinky: What do you call a fat parakeet that’s made out of chocolate? (The answer: pudgy fudgie budgie) (And you might suggest that children research why a parakeet can be called a budgie.)

Now for Some Math Related Riddles
I didn’t provide answers for these. Let me know if you’re completely stuck.

What’s a number that doesn’t cost anything?  (hink pink)

What’s a number that’s the color of the sky?  (hink pink)

What’s guaranteed to make you laugh for five cents?  (hinky pinky)

What do you call a number that didn’t arrive on time?  (hink pink)

What do you call two and a half dozen kids who have been camping for a week and didn’t take a shower for the whole time? (hinky pinky)

What do you get when you pay a friend two quarters, four dimes, and two nickels for a good loud yell?  (hinky pinky)

MUTTERING: My Tip for Making Up Riddles
When I wrote The Hink Pink Book, I wandered around the house for days (maybe weeks) muttering words that rhymed and jotting them down. I’d select a word, say three, and then start my muttering, going through the alphabet:
bee, fee, flea, free, he, me, pea, plea, sea, see, tea, wee, . . .

Then I’d see if any riddles came to mind. For example:
What do you call baby triplets? (hink pink) (The answer: wee three)

I’d also think about rhymes with more than one syllable:
agree, disagree, emcee, degree, oui (why not other languages?), gluten-free, thirty-three, . . .

There’s no end.

A Challenge
I haven’t been able to think of a math related Hinkety Pinkety? Any ideas?

Maybe post riddles on Twitter using the hashtag #hinkpink?

P.S. The book from my shelf is one that I had given to my parents and has migrated back to me. This is the inscription I had written. I still think it’s important to be silly once in a while, maybe even more often.