"The pervasive use of nicknames in this way apparently comes from the old belief that evil spirits are constantly on the lookout for newborn children to snatch away and control, but using a nickname instead of a normal Thai name confuses the spirits and helps to keep the child safe."
The weirdest Thai nickname I noticed was Shampoo I think lol
nicknames are easier to remember. example, my nickname is maya. my real name is so long, it would just be a hassle and frustrating to say it every time someone says my name. real thai names are used more for official use. but i do have friends that use their first name as their nickname if it's short.