A semi-endearment is a phrase used when puzzlement would be an acceptable outcome. It is ok to use a semi-endearment when you know a person well. But a little inappropriate as the semi-endearment can be a bit rude - but quite ok after an explaination.
Some examples of a semi-endearment are gruffalo or penny pockets. "oh here comes penny pockets" "here comes the gruffalo"