It's a frog! It's a bong!
It's a ... frong?!
These playful water pipes have the down stem built into them, which allow them to be used with any 14mm bowl.
It's easy to fill them with the correct amount of water - after filling just hold the mouth hole vertically until no water is running out of the down stem. This should leave the down stem partially covered with water and will produce a delightful bubbling sound.