Here are some examples of how "pernicious" might be used:
* "The pernicious effects of smoking are well documented." This implies that smoking is harmful, but the damage is gradual and might not be immediately apparent.
* "He spread pernicious lies about his political opponent." This indicates that the lies were harmful and intended to damage the opponent's reputation.
* "The pernicious influence of social media can be seen in the spread of misinformation." This suggests that social media has a negative and damaging impact on society, even if it's not always obvious.
Note: "Pernicious" is often used in more formal settings and can sound quite serious.