As in, just fell off the.
And just as a review:
green (?ri?n) — adj immature, unsophisticated, or gullible
If you were wandering how much contextualization is required to understand this, spend some time discussing it with a seventh-grader. Or trying to – it’s difficult but a reminder of just how far you have to back up to bridge the chasm between the (to me) unseemly elation and unnecessary fear the event may have engendered.*
* Obviously applicable to many events, conditions and situations likely to be encountered.