If you’re trying to learn Thai you’re probably heard it said that you should put Krup or Kup on the end of everything you say as a man, or as a woman, use “Ka”.
USE IT! I can’t tell you the number of times I’ve heard foreigners blurting out poor Thai without kup at the end of it. Thai culture is based on respect for the other people you’re interacting with. Even if a Thai can’t stand the other person he/she is cordial to them, smiling, and saying kup or ka a lot.
When you speak without ever using the polite phrase in your speech then it says something about you.
1. You don’t care enough to use it.
2. You didn’t learn it, so probably you learned from someone in society that didn’t use it themselves.
Either way – it’s impolite and says something about you that you probably don’t want to say about yourself. Use “kup” and “ka” often and you’ll get more respect from Thai people.