viscid liquid
If it were a Hink-Pink, it could be "a thick brick." Actually, the question is about Hink-Pink according to the original source for the question which is a book for gifted students. The section of the book asks about both hink pink and hinky pinky, and the question is in the hink-pink category on the page.
Hink-pinks are usually adjective-noun combinations. That question is usually "What is a hink-pink for an artificial body of water?" The answer is a "fake lake."
spring ring
water daughter
water daughter
Water
fake lake
fake lake
fountain mountain
Thin inn is the hink pink for skinny hotel.
The hink pink for "boy's test" is "lad's quiz."
big twig