A 'LUG' (Lesbian Until Graduation) first came to be in some Northeastern preppy universities. Reason; tell your male date that your lesbian to avoid sex. The LUG scenario then migrated down into the better high schools for the same reason.
Sadly (for some) the LUG story was not fully understood at the high school level and the 'L' in the LUG scenario actually became a reality for some girls and the rest is history - as they say.
I had forgotten about that! I wonder how many girls are still using that one?