Senoufou: "Taffia" is any group of Welsh people who practice nepotism or live in an ethnic enclave.

See Wiktionary.

It is a standing joke that, in the enclosed communities of the valleys, it is sometimes impossible to avoid nepotism. It is also a joke that corruption is what you suspect when the man awarded the contract is not related to anyone on the planning committee.

There is also the one about the well-off Englishman who is building a second home for himself in West Wales (a perennial source of discontent). Annoyed at the lack of progress, he asks the builders' foreman if there is any Welsh equivalent to the Spanish word "Mañana". The foreman thinks about it for a while and replies "Nothing that conveys quite the same sense of urgency."