That was a tricky one because there are so many slightly different versions of it. A quarter of a century ago a young friend of mine used to chant it almost incessantly but as "Inky dinky donky, Daddy bought a donkey". Google finds it as "Inky pinky ponky, Daddy had a donkey", "Inky binky bonkie, Daddy had a Donkey", ""Inky Pinky Ponky, Father Had a Donkey" and so on.
The ryhme turns up on Youtube videos of nursery rhymes, such as this one . .