The Starbucks manager is instead referring to the Starbucks Doubleshot on Ice you'd get in the store, made fresh. "The Starbucks Doubleshot is cheap and potent," she says. "Iced coffees have a lot of caffeine and are cheap." She's not kidding -- the Doubleshot on Ice has 225mg of caffeine. That's a ton more than the Doubleshot served hot, which has a mere 110mg of caffeine.
Keep in mind that an average 8oz cup of coffee has 95mg of caffeine. So you're getting two cups' worth of caffeine in one iced drink. If you want a delicious Starbucks drink but don't care about the amount of caffeine, we've tried every single drink on the menu and know what's best.