Gary losing a nipple back in the Season 4 premiere seemed like a one-off twist played for laughs, but the loss came back with a vengeance due to the demon Neron, and his actions last week proved that restoring the nipple came with with powers.
In case there was any doubt that Legends of Tomorrow is the most bonkers superhero show on network television (now that Gotham is done, anyway), then “Nip/Stuck” using Gary’s nipple to do a lot of damage should have laid those doubts to rest.