Mr. Crocker builds a portal to Fairy World, but it instead turned him into goo. Denzel's mother Dolores-Day tells him he wasted his life chasing fairies (all the while, whacking him with a broom, even when he restores himself to normal). So he picked her up and froze her with a freezer gun. Crocker then goes to his wheel of destiny to find a new vocation. The first that comes out is Women, but Crocker says "Let's be realistic" and the wheel ended in leprechauns. He finds it the perfect fit, as leprechauns can't fly and isn't magical like fairies can and they have pots of gold. Because he can't go to Ireland on a teacher's salary, he instead settles for Little Ireland, an Irish-themed neighborhood in Dimmsdale.
There, Cosmo is telling his family about Leprechanuka, a holiday in which the Great Potato comes to give joy and happiness. Because Cosmo was dressed as a leprechaun, Crocker captured him and demanded gold, so Cosmo gave him a pot of gold. When he returns, Wanda tells him that he can't poof up gold, so he replies he took it from the McPunchies clan, a group of tough leprechauns. The McPunchies appear and demand their gold back. Timmy tells Big Dave (the leader) that Crocker has it, so his brothers Lucky and Greeny take Wanda and Poof while Dave, Timmy, and Cosmo go to recover the gold. It turns out that Mr. Crocker spent it all at a superstore called Big $tuff, and bought among the stuff, a talking car. When Timmy tells him Crocker needs the gold, Denzel replies that he spent it all, and Dave demands it back or else. Crocker attempts to leave, but Dave gives them until the end of Leprechanuka to recover the pot o' gold (Timmy's surprised to learn that Leprechaunaka's an actual holiday).
They attempt to win it, so Cosmo and Timmy enter a skating contest, where if they get triple 10 they win, but Crocker was a judge and gives them and F (out of habit), so they lose. They go to a gold mine, where Cosmo warns them of the eighth dwarf, Crazy, who is giant and attacks them with a chainsaw. The time ends and Dave takes Crocker to his realm. Timmy and Cosmo follow them and they are lead to Ireland. Wanda and Poof were having a great time, eating Lucky Bits.
Dave returns and asks Greeny and Lucky to get him the human vaporizer, but they can't find it cause everything's green in Ireland. When Timmy and Cosmo arrive, Dave says he'll cook the four of them. Then Cosmo's belief in the Great Potato brought it to life, and it asks Dave why do they want the gold. They really wanted the pot, cause it's a family relic. The talking car says it's in the trunk, and they recover it and leave. Crocker wonders why he is around fairies when he chose a different path, so he returns home after seeing leprechauns are too much. Denzel tries his luck with the Wheel of Destiny again and it tells him dwarves, but after his experience before he tries again and it ends on Fairies so everything is normal again.