Want to compliment your girlfriend while looking smart at the same time? Try saying she she has a callipygian figure. It means she has a shapely rear end. Then again, you might just want to stick to saying she has beautiful eyes.
Callipygian comes from the combination of the two ancient Greek words for "beauty" and "buttocks" and was famously used to name a naked statue of the Greek Goddess of Love, the so-called Aphrodite Kallipygos, who fetchingly raises her robe to reveal her charms beneath. True linguists among you might wish to travel to the National Archaeological Museum in Naples, Italy to view the Roman copy of the original.