Lucy ends up stripping off her boyfriend Mario Falcone and measuring his penis to help her design a unique vodka ice sculpture.
"I don't get how it fits in with your American Prom theme," says Mario. "Why would there be an ice sculpture with my cock out?"
Lucy laughs: "Because American Proms are really over the top and I want everyone walking in and the first thing they've got to do to get the party started is take a shot of vodka from your willy!"
Mario replies: "The thought of Nanny Pat taking a shot of vodka from my willy is disturbing." Lucy jokes: "I think Bobby will be there all night."
Elsewhere, Lauren Goodger attempts to rekindle her friendship with the Wright family and Arg reminisces about his love for Lydia Bright.
Meanwhile, Gemma Collins has yet another bust-up with Bobby and Charlie
The Only Way Is Essex finale airs on Sunday. The show will return for a seventh run in the autumn.
[TOWIE Series 6 - Photo Gallery]