A hink pink for a giant mermaid could be "big wig." Hink pinks are typically rhyming pairs of words that describe something, and in this case, "big" refers to the giant aspect while "wig" playfully captures the idea of a mermaid's flowing hair.
flat hat
Thin inn is the hink pink for skinny hotel.
The hink pink for "boy's test" is "lad's quiz."
lathering gathering is the hink pink for a group of men shaving
"Man pan" is a hink pink for male pot or masculine skillet.
Dark ark is a Hink-Pink for Noah's boat with the lights off.
The hink pink is clean teen.
pink mink
"Ground mound" is the hink-pink for "dirt heap."
hot pothot pothot pot
Oh, dude, a hink pink riddle for a box for huge rocks would be a "massive boulder folder." It's like a rock's version of a filing cabinet, you know? So, if you ever need to organize your giant stones, just grab your massive boulder folder and get to work!
Lunch punch! :) These hink pinks are HARD!