Activate Sling-Gang Lieutenant by sacrificing Putrid Goblin.
When Putrid Goblin dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Rhythm of the Wild.
Resolve the Sling-Gang Lieutenant ability.
Repeat.
This loop turns a humble goblin into an endless cycle of sacrifice by letting Rhythm of the Wild completely neutralize the downside of Putrid Goblin's persist ability. Because Rhythm of the Wild grants nontoken creatures riot, Putrid Goblin enters the battlefield with a +1/+1 counter that immediately annihilates the -1/-1 counter it would otherwise carry from persist, keeping the loop wide open. Sling-Gang Lieutenant acts as both the executioner and the ultimate payoff, draining opponents' life totals through a relentless stream of goblin sacrifices and entering tokens.