Crystal has kinda wacky blood circulation due to her artificial heart. It does the best it can to keep her physically going but her hands and feet are the coldest parts of her body. Overall, her body temperature is one of the coldest in Briar Patch to some concerning degrees even though it doesn't seem to effect her much.
Crystal is also a bit of a prankster.
Which means there have been multiple occasions where she's snuck up on someone and put her cold ass hands on the back of their neck, leading to said person screaming both from the shock and the cold.
She's gotten nearly everyone save for Miss Castor (nobody pranks her out of respect), Nana (she knows she'd kill her), Pinokuni (he can't really feel temperature like that), Ben (his fur is too thick), and Kai (he's such a nice guy that she feels bad).
Piper is a bit of a mixed bag because he doesn't get all too surprised due to his heightened hearing and the cold reminds him of home since it's damn near always snowing where he's from so he doesn't mind the sudden cold hands that much. He's like...the only one who can really laugh things off.
She got Paulie once and it triggered his frog instincts, specifically the need to hibernate, and he passed the fuck out on the floor right there. He woke up seconds later and gave her a piece of his mind but Hazel and Kettle thought it was funny as hell.
Crystal has also scared Jack quite a few times and it was some of the highest pitched screaming she's gotten from her trick she's heard in her life.