Farang (outsider/Westerner) + ding dong (silly, bell-like, or phallic) =
You may be looking for one of these real things: farang ding dong wiki
Given that, this paper will instead:
Farang Ding Dong, also known as Phraya Phahonphonphayuhasena or King Naresuan, is a significant figure in Thai history. However, I believe you might be referring to a different individual, as there seems to be some confusion. Farang (outsider/Westerner) + ding dong (silly
The phrase appears to be either:
When combined, the phrase describes a foreigner who is behaving in a way that Thais find nonsensical or amusingly erratic. Cultural Context and Usage farang ding dong wiki