The word
walkaton ('walkathon') gets used quite often in Malay, as in this extract from page 2 of
Media Permata of 23 April 2012:
Larian amal ini dibahagian kepada dua- larian 6.3 km, dan walkaton 4.2 km.
which might be translated as
This public run is divided into two: a 6.3 km run, and a 4.2 km walkathon.
It is interesting that the silent 'l' in
walkaton is retained in the Malay word, but the 'th' becomes 't'. I'm not sure why this differential treatment of these letters occurs. One possibility is that the vowel in the first syllable is neither [o] nor [a] when it is pronounced in Malay, so neither 'o' nor 'a' would be suitable in spelling the word; but the consonant at the start of the final syllable is always pronounced as [t] so it is fine to spell it as 't'.
One way or another, given that so many borrowed words with 'th' in the original have 't' in their Malay versions (
terapi, teori, tema, ...), it is hardly surprising that local people tend to use a [t] when saying these words in English.
