塗鴉

From a poem by Tang-dynasty poet Lu Tong.

忽來案上翻墨汁，塗抹詩書如老鴉。 [Classical Chinese, trad.]
忽来案上翻墨汁，涂抹诗书如老鸦。 [Classical Chinese, simp.]

From: 9th century, Lu Tong, 《示添丁》(Solemn Instructions to the Toddler Boy)

Hū lái àn shàng fān mòzhī, tú mǒ Shī Shū rú lǎoyā. [Pinyin]

All of a sudden you flip o'er the ink — gone are the Canons now daubed like a crow.

塗鴉

1. (often humble) to write (characters, calligraphy) or draw (painting) in a casual, poor or unaesthetic manner; to scrawl; to scribble

   犬儒惜墨如金處，虎將塗鴉以血時。 [Classical Chinese, trad.]
   犬儒惜墨如金处，虎将涂鸦以血时。 [Classical Chinese, simp.]

   From: c. 1963, Nie Gannu, 《訪丘東來烈士陵園故居》

   Quǎnrú xīmòrújīn chù, hǔjiāng túyā yǐ xuè shí. [Pinyin]

   Where a petty scholar stints on the ink, the warrior scrawls liberally with his blood.

2. to write graffiti; to graffiti; to vandalise

   禁止塗鴉！／禁止涂鸦！  ―  Jìnzhǐ túyā!  ―  Graffiti prohibited.

   牆上的塗鴉／墙上的涂鸦  ―  qiáng shàng de túyā  ―  graffiti on the wall

• (to write graffiti): 漆鴉／漆鸦 (qīyā)

• 刻畫／刻画 (kèhuà)