SINGAPORE - When American linguists Keri Matwick and Kelsi Matwick came to Singapore in 2018, one thing that caught their eye was toilet etiquette posters featuring the use of comics.

Dr Keri Matwick, a lecturer at the Nanyang Technological University's (NTU) School of Humanities, says she and her twin sister found these posters "humorous but complex" as they were not common in other countries.