The 24-year-old Stoke-on-Trent nightclub promoter's revelation was shown during last night's (July 25) highlights show.
After seeing the testicle, Becky Hannon said: "I have never seen a bigger bollock in my whole life."
She then brought Scott Mason over to see the private part.
Explaining the medical condition that had caused the growth, Luke S said: "It's full of veins."
A stunned Adam Kelly merely commented: "Oh my God!"
Luke S is one of eight housemates facing the public vote and possible eviction this week.
Big Brother continues daily on Channel 5.
