As a mum of a couple of teenagers and "tweens", I have come across some rather strange nickname variants, especially recently. One of my dc has a normal, standard shortening of his name, (think Alexander - Alex or Samuel - Sam), but one has a rather odd nn which started out as a family thing as a small child and has, as she's got older, worked it's way into friends calling it her - - it is "La" or "Lally" as a short version of a not-common-but-not-weird Gaelic/Scottish girl's name.
Some others i've come across are "Chekky" for Francesca, "Boo" for Rebecca, "Tits" for Titania and "Tats" for Tatiana (I am not kidding), "Mimmy" for Imogen, "Nan" for Natasha, "Ocki" for Octavia, "Roo" for Rosie (I think her name is actually Rosanna)
It seems to be more of a girl thing to shorten the name for some reason. Interesting.
Any "unusual" nicknames in your family or friends? I would like dd to not be called by this slightly ridiculous nickname if at all possibl, but I suppose when they get to a certain age you can't stop them!