In the annals of weird, this has got to rank near the top. The Darwin’s Frog practices a child-rearing technique known as “mouth brooding”. The mother lays the eggs, which the father guards until they hatch about two weeks later. He then gathers up the tadpoles in his mouth, swallows them into his vocal pouch, and there they stay until they’re fully formed.
This video shows the young frogs hopping out of their father. It must be uncomfortable for him with all those little ones kicking his insides.