A few other popular "passwords" are exchanged -- including an insult to Vladimir Putin.
Nazar and Yaroslav then explain that they hope to join the army when they are older, to "support the Ukrainian armed forces".
Yvanik says he is proud of this new "patriotic" generation.
"They understand that the enemy came to kill us," he told AFP.
On the other side of the village, 15-year-old Arten and his three friends Pavlo, Ivan and Andriy are waving a big Ukrainian flag in front of their hut on the side of the road.
They are stopping cars too, but offer tea and coffee.
"We check their documents and car registration papers," says Arten. "We are here all day every weekend."
Asked if they consider themselves to be "patriots," they answer "yes" in unison.
A few dozen kilometres away, 10-year-old Maskym is wearing a military coat covered in badges and a plastic helmet.
Carrying a wooden rifle, he waves to passing Ukrainian soldiers.
"I gave the army 15,000 hryvnias ($400 USD)" he proudly tells AFP journalists.
"I like to help people and make them laugh," he says before heading back to his post next to a pretend artillery unit and rocket and a Ukrainian flag.
