Anyone know anything about this mug?

Found this little guy today. It is a small 2 faced stackable mug. The bottom reads "Hills-Made by Fralin". It has a small green ceramic frog in the bottom. I was thinking it is a hobbyist mug, but I thought I would see if you guys knew anything about it. I can't seem to find anything simliar on OOga Mooga, Thank you in advance!

not sure but see if the frog gurgles/bubbles when you put liquid in the cup. I have a coffee mug from Orvis like that - never seen tiki mug though.

I put some water in it, I didn't notice anything unusual.

I think your first instinct is correct; that it's a hobbyist stacker mug.

Here is one from my collection, different glaze and sadly, no croaker inside!

These are definitely hobbyist mugs.

Depending on the mold, they may or may not stack.

The blue one is from a similar production. I can get the green one to stack on the blue, but the blue base is too big to stack on the green.

PTD

Mike - There are a few of these on Ooga-Mooga, but there isn't a template yet. I'm pretty sure that the mold was manufactured by Duncan Home Ceramics.

Good info as always, Thanks to everyone who responded!

Heading to an estate sale this morning, hoping for more interesting finds. :)