That would be great, if they could pull it off. Unfortunately, they haven't been able to, so it just comes across as them tacking the school stuff on because high school comedies are popular right now.
A geas is a a vow, obligation or doom placed on someone (it comes from gaelic mythology). Lelouch's power is to put a geas on people. The Japanese producers used the mis-spelling, which doesn't excuse the fansubbers from expounding on it.
It got ridiculous. Sticking the occasional billboard or such in the background is one thing, but when product placement starts intruding on the dialog, it's too much.