Thailand

Almost every word which starts with the letters 'th' is pronounced with a dental fricative, either [θ] or [ð], in most varieties of British and American English. Exceptions are the names Thai, Thailand, Thames, Thomas and Theresa, and the herb thyme, all of which are pronounced with [t] at the start.

In this part of the world, Thai and Thailand are sometimes pronounced with [θ] at the start. I always assumed this was hypercorrection: speakers have learned that standard pronunciation has a dental fricative whenever 'th' occurs, and so they sometimes apply this rule where it does not in fact apply.

However, one of my UBD colleagues offered an alternative explanation: in Malay, tahi means 'faeces'; and in ordinary speech, the [h] may be omitted so the word is pronounced as [tai]. It is therefore possible that people are using [θ] at the start of Thai and Thailand to avoid sounding rude.