Formal:
* "The novel's overly elaborate prose and convoluted metaphors were seen as pretentious by many critics."
* "Her pretentious pronouncements on the subject of art revealed a lack of genuine understanding."
* "He attempted to impress his guests with pretentious displays of knowledge, but his efforts only came across as insincere."
Informal:
* "He's so pretentious, he even uses a French word for everything."
* "That new restaurant is so pretentious, you have to wear a jacket and they only serve five-course meals."
* "Don't be so pretentious about your new job; we all have to start somewhere."
Sarcastic:
* "I love the way he tries to sound so sophisticated, it's so pretentious."
* "She's so pretentious, she even buys her dog organic food."
* "He's so pretentious, he thinks his opinions are actually facts."
Remember, using "pretentious" often implies a negative judgment. Consider the context and tone carefully when using this word.