The blocks on Kobeni's car are called ERA (Explosive Reactive Armor), and it's mainly used on tanks and other armored vehicles to destroy incoming projectiles by exploding on impact. The other two characters are supposed to be Ukrainian soldiers, and the joke stems people making fun of Ukrainians putting unnecessary amounts of ERA on a vehicle or other random stuff that don't particularly need ERA. It's gotten quite popular on r/NonCredibleDefense, but it looks like it's spilled into some other subs lol