Weird World of Nicknames

I was just pondering deep stuff tonight, like, how do we end up with nicknames that are so odd? We have the typical shortened forms of names, but then a couple of funny ones that may need explanation too. I thought I'd document them here for posterity.

Isaac Michael's names:
Ize - just shortened, first used by Abigail
Ize-aroni - silly, made up by James
Buddy - what I call him lots of the time
Scooter - what my Dad and I called him most of the time when he was a baby
Augustus - somehow James came up with this one day, probably after watching Willie Wonka and the Chocolate Factory, and it must be pronounced in a bad British accent
Prancing Pony - what James says would be Isaac's Native American name, due to his habit of walking on his tiptoes
I-Man - given by the announcer for basketball this year
Hardus Headus Maximus - from James, self-explanatory for our stubborn, or tenacious, boy

Abigail Rose's names:
Abi - her name shortened
Rosie - James' name for her
Abi-girl - my name for her, probably from the Anne of Green Gables "Anne girl" as Marilla called her
Abi Rose - my brother Jacob's name for Abigail
Baby - what I call her often
Snuggle bunny, snuggle bug - she is extremely cuddly, so these always apply
Penelope - used in conjunction with Isaac's "Augustus"
Nosey Rosie - unfortunately fits very well
Ol' sweetness - not sure how or where, but a name I have used since she was a baby
Ces couches (or a variation, ces coucheres) - this gem came from the French phrasing on a box of diapers that I noticed when she was tiny, and it cracked me up, so for some reason, I'd call her these names, complete in a Julia Child voice....yeah, I realize it makes no sense to call her "diapers"