Yesterday my wife posted birthday greetings in English on Facebook. One of her friends wrote something in Korean which Facebook automatically translated as ‘Ugly [smiley face]’. ‘Congratulations’ in Korean is 축하해요 (chuk-ha-hae-yo) normally and 축하합니다 (chuk-ha-ham-ni-da) formally. The verb ‘[subject] am/is/are ugly’ is 추해요. An unaspirated stop like ㄱ followed by a ㅎ is always pronounced as the corresponding aspirated stop, in this case ㅋ, so 축하해요 is pronounced 추카해요, which is what the friend actually wrote. Facebook’s translator (and Google Translate when I experimented) interpreted 추 as the verb stem of ‘ugly’ and ignored the 카, which is meaningless if 추 is interpreted as ‘ugly’. It also ignored the verb conjugation.
PS I asked my wife about this. She said that people sometimes write 추카해요 in text messages or social media posts, but 축하해요 is definitely the correct spelling, and people would never write 추카해요 in any formal context.