* The rumors spread insidiously through the office, poisoning the atmosphere with suspicion and distrust. (Here, "insidiously" emphasizes the subtle and harmful way the rumors spread.)
* The disease worked its way insidiously through his body, leaving him weakened and vulnerable. (This example highlights the gradual and deceptive nature of the disease's progress.)
* The advertising campaign insidiously appealed to people's insecurities, making them feel inadequate without the product. (This sentence emphasizes the manipulative and deceitful nature of the advertising campaign.)
* He was unaware of the insidiously growing resentment within his team, fueled by his unfair treatment. (Here, "insidiously" describes the hidden and dangerous growth of resentment.)
* The politician's charisma was insidiously effective, masking his true intentions. (This sentence describes the deceptive way the politician's charm hides his real goals.)
Remember, "insidiously" usually carries a negative connotation, implying something harmful or deceitful.