[Peep Show] Cally, briefly a love interest for Mark and Jez's one time manager, did not believe in Crystal Skulls and only faked it as a ploy to see if their relationship was feasible for her

Cally is shown to be an intelligent, competent and straight-forward woman and by her own admission she is not someone who entertains bullshit. Yet her belief in the power of crystal skulls runs contrary to everything established about her character up to that point, much to the chagrin and bemusement of Mark who has fallen for her callous no-nonsense business woman approach to her day-to-day life.

Before the two's relationship has even begun Cally asks Mark to join her for an event a friend of hers is hosting in a new age bookshop filled with spiritual tat. The two bond over deriding the stores stock as 'bullshit'. Until they get to the skull on display which Cally immediately starts gushing over to the confusion of Mark. She then tells him that if the two's relationship is to succeed she has to know he believes in the power of Crystal skulls. He sheepishly concedes and tells her he believes they're magic and crafted in Atlantis

What if the crystal skull wasn't simply a vehicle for conflict to arise in Cally and Mark's potential romance (in the usual Peep Show fashion) and by extention be a symbol of mark's willingness to sell out his beliefs for fear of dying alone. But instead was a ploy by Cally to see if she could control Mark and expedite the courtship process with the skull becoming a symbol of the power she wields over him.

Evidence: ^^^admittedly ^^^scant

Mark and Cally first meet after the latter's fling with Jez where she bemoans her struggles to find "cash rich, time poor" singles more befitting her lifestyle. This aligns with my speculation that she's using the ploy as a way to quickly establish whether she holds the power in the relationship dynamic without having to wade through dates to see if he is or isn't going to bend the knee to her and the time wasted being a sunk a cost. So while she might not believe in the 'magic' of the skulls she wasn't necessarily lying when saying that Marks belief in the skulls was important to her. Marks inner monologue is literally saying "please don't make me believe in Crystal Skulls" which may tip this theory into the realms of being intentional writer's subtext as opposed to being a theory

Cally warms to Mark after she infers that he had no qualms sidelining Jez in favour of Super Hans, she tells him he's "a real piece of shit" with glee as though that's something to aspire to. Because in her world it is something desirable and Mark straight away ticks a box for her.

She immediately asks him out on the date to the 'hippie shop' presumably on account of being impressed of how much of a shit Mark is, and there begins Callys informal interview process for her new sexual partner. Immediately after Mark proverbially rolls over for her the scene cuts to the two immediately after sex where she gives mark negative feedback before training him. Almost like an employer, again Mark's inner monologue hints at this dynamic "I'm a sex robot and I'm servicing The One".

When Jez discovers he's been phased out of the band by Cally (via Mark the subservient messenger) he decides to thrash Callys festival trailer. Mark takes the opportunity to destroy the Crystal Skull and in doing so ruins the magic by shattering the symbol of Cally's dominion over Mark and the relationship dies soon after on account of Jez telling her that Mark destroyed the skull before lying that he thrashed the trailer in anger having being told what to do in bed and at the treatment of Jeremy neither of which was true.

I know theres a lot of presuming, assuming and extrapolating going on in this theory but I do think that it aligns with how Cally is presented throughout the episode shes implied to be smart, powerful, successful and while she has no tolerance for bullshit from others she's got no issue slinging it herself as shown by the fact literally everything she says to the band is either outright lies or half truths - "they listened to your CD and they loved it, they don't want you playing Festivus" - "I spoke to hans and he loves your idea" - so I could easily see her lying in her personal life as well as her professional life.

Plus, again, the Crystal Skull sculpted by Atlantians does seem a bit out there for someone who comes across as such a meat and potatoes, straight up-and-down, beef Wellington, don't trust the argies, dick in vagina, cheddar cheese and chicken tikka masala sort of woman. What do you think? Is she for real? I don't know. Its hard to tell

This could be slightly insane rambling and this post was only written on account of me not being able to sleep so there's a very real possibility it makes very very little sense.

It's also very possible this was intentional subtext from the writers that was never explicitly stated but plain to see for observant viewers in which case I apologise.

TL:DR: business savvy contract lawyer with admittedly too little time to properly partake in the dating scene feigns an interest in one aspect of the occult to determine if a potential romantic partner whos also a sceptic is willing to indulge her belief in Crystal Skulls to streamline the dating process and to gauge Marks devotion to her.