The extremely safe method to not have children, consisting of waiting four years with a boyfriend/girlfriend before having sex. Also can be taken as 1 base for every year.
Mike: "You hit that yet?"
Skeeter: "Naw man, only half way through that four-year-plan. Sho aint gonna be paying no child support though, YADADAMEAN?!?"
The tendency of otherwise straight girls to decide that they're gay during their time at Smith College, only to realize that they're not shortly after graduation. See also smithies
I knew this great, beautiful girl who went to Smith. I had a huge crush on her, but she was gay...or so we thought. Turns out she was on the four-year-plan, and now she's in New York and has a *boyfriend*!