Summer Kid
A kid, usually in Middle or High School, that in the summer looses track of time, what day it is, and also does not shower for a long time because they do not need to impress anybody at school.
I had Joey over yesterday and he smelled like dog poop. What a Summer Kid!
Summer kids
When someone has more than one kid and does not keep them... The kids are being raised by in different households.
When asked " does she have any kids?".... Answer -- "she has summer kids. Meaning Some are here and some are there."