With that, Downs began the Half-Gallon Challenge.
For the past three decades, long-distance hikers arriving at the midway point of the 2,180-mile Georgia-to-Maine footpath have made it a tradition to stop at Pine Grove Furnace State Park in south-central Pennsylvania and eat an entire brick of ice cream.
The reward: bragging rights, a small commemorative wooden spoon stamped in red letters with "Member of Half Gal. Club," and quite likely an upset stomach or a nasty case of brain freeze.
About 350 thru-hikers each year successfully complete the gastronomic feat, according to Don Ray, who managed the park store for a decade. But it's not easy, even for trail-hardened hikers who can burn 4,000 to 6,000 calories a day and still lose weight while consuming vast quantities of food.
Former thru-hiker Jessica Lafortune recalled feeling heavy and lethargic yet a bit jumpy from the sugar high after polishing off a half-gallon of cherry jubilee. For the record, that's 16 regular servings, 2,400 calories, and 112 grams of fat.
"You just want to lie down in the middle of the trail and sleep it off," said Lafortune, 28, a former banker who walked the trail last year and now works for the Appalachian Trail Conservancy.
She had no regrets, though.
"It's a hiking tradition I did not want to miss out on. And I really wanted the wooden spoon."
Nearly every thru-hiker has heard of the challenge. Many take it seriously, racing one another and timing themselves with stopwatches. Appalachian Trail lore says that if you finish your carton, you get it for free, but that's incorrect: Everyone pays $5.95.
Store worker Barb Delgado believes that Neapolitan is the easiest to take down because it's smooth and the flavors are varied. She considers the hardest to be cherry jubilee and moose tracks - because of the chocolate chunks.
Delgado is also a Half-Gallon Challenge purist.
"There are cheaters who melt it and drink it, which I don't consider done right," she scoffed.
Hikers are invited to record their successes in a black-and-white composition book in the store. Nearly all the entrees are signed with "trail names" instead of real ones.
"1/2 gallon challenge. Chocolate. As if that's not obvious now," wrote a thru-hiker named Gingersnap, referring to the dark-brown smudges left on the page.
"I told my mom about this challenge," said another. "She was like, (Wobegon), you don't even like ice cream. I still don't."
Moaned a hiker named Jukebox: "Mint chocolate chip down in 40 minutes. I'm gonna die, bro."
Josiah "Mehap" Cilladi of Parkesburg, Pa., and Tim "Grasshopper" Trickel of Raleigh, N.C., had no such trouble with the Half-Gallon Challenge. Having just completed a 22-mile stretch of trail, they arrived at the Pine Grove Store at mid-afternoon Thursday and popped open fresh cartons of chocolate.
Grasshopper finished in 42 minutes, Mehap right behind him in 45, and they didn't even soil their trail beards.
"That was not as hard as I expected," Grasshopper said. "I could eat a cheeseburger. I could go hike another 10."
At the lake, Downs, 23, a Clear Spring, Md., resident who goes by the trail name of Lemur, dispatched half his carton with relative ease. Then he started feeling nauseated, each melting spoonful of chocolate goo more difficult to get down than the last.
"Two months on the trail, and this is one of the worst days," he said.
An hour and 15 minutes after starting, his carton finally empty, Lemur lay face down and spread-eagled in the grass. He hadn't intended to spend the night at Pine Grove Furnace, but hiking to the next shelter was out of the question.
Thursday afternoon - 24 hours later - he was finally ready to resume his northbound journey. Lemur looked none the worse for wear as he hoisted his pack onto his shoulders.
"I'll probably never eat chocolate ice cream again," he said.