A "red eye" coffee, also known as a "shot in the dark" or a "depth charge," is a type of coffee drink that combines regular drip coffee with a shot of espresso. The name "red eye" comes from the reddish appearance of the drink when the dark espresso mixes with the lighter coffee.
To make a red eye coffee, a barista or coffee enthusiast typically starts by brewing a regular cup of drip coffee, which is a standard black coffee made by passing hot water through coffee grounds. Then, they add a single shot of espresso to the drip coffee, creating a bolder, more caffeinated beverage.
The red eye coffee is popular among those who want an extra kick of caffeine to boost their energy levels, as the combination of regular coffee and espresso results in a stronger brew compared to a regular cup of coffee. It's a drink of choice for people who need a quick pick-me-up or an intense caffeine jolt to start their day or keep them going during long hours.
Keep in mind that the names of coffee drinks can vary regionally or even between coffee shops, so you might come across other names for this drink depending on where you order it.