Abbreviation for "Tiong Kok Lang". A Chinese dialect term used in parts of South East Asia and Taiwan to represent a person born in China. The English equivalent is "Chinaman", which although is not deemed offensive by older dictionaries, it is deemed degrading in some cultures and modern dictionaries because it usually represents a person who is lazy and complains a lot. In some cultures and societies, it also represents and has references to poor hygiene and social grace.
John is damn lazy, he is no different than a tkl.
That tkl constantly produces work of no standard!
Tkl's are smelly and spit everywhere, they have no social manners!