Definition 1 of 1
It comes from the Tamizh (the Tamil word for Tamil with an ending that is not to be tried alone or without quick access to a psychiatrist.)
A classic example of Thanglish is the song Why this Kolaveri Di, that has viral legs beyond expectations on YouTube.
A more wonderful exposition are robe found in the early songs of T.M. Sounderrajan in Manam Oru Kurangu:
Also check out the amazing - Come on enjoy summer season bit in Kashmir Beautiful Kashmir in classic Thanglish.