Meaning:
“画风” means “style of painting,” and “突变” means “sudden change.” Literally meaning “a sudden change in one’s style of painting,” this term has been used as a metaphor for sudden drastic changes in a person’s traits, appearance or world view, or abrupt changes in things and their course of development.
Example:
A: 昨天丽丽家的聚会你去了吗？有什么趣事吗？
Zuótiān lìlì jiā de jùhuì nǐ qù le ma？Yǒu shénme qùshì ma？
Did you go to Lili’s home party yesterday? Anything funny?
B: 去了。我们同事中有个特别沉默内向的男的，喝了点儿酒，结果画风突变，不停给我们讲笑话，笑得我肚子痛。
Qù le 。Wǒmen tóngshì zhōng yǒu ge tèbié chénmò nèixiàng de nánde，hē le diǎnr jiǔ，jiéguǒ huàfēng tūbiàn，bùtíng gěi wǒmen jiǎng xiàohuà，xiào de wǒ dùzi tòng。
I did. One of our colleagues, a very silent and totally introverted guy, became another person after a few drinks. He told us one joke after another, and made me laugh a lot.