I neglected to mention two that aren't strange to me, but which drive some extended family members nuts.
I really can't say how it started, but...
We have a daughter and a son.
At some point in their childhood, we started calling them "Boy" and "Girl"
"Hey Boy, how was football?"
"Girl, could you hand me the remote?"
If we're talking to a relative, we might say "Girl's out walking the dogs." or "Boy is so sick of chemistry this year."
We've been lectured because apparently we're erasing their identity or some such...