Here are some ways you could express the meaning of "boo" in Korean depending on the context:
For surprise or fright:
* 깜짝이야! (kkamjjak-iya!) - This literally means "I was startled!" and is the closest equivalent to "boo" in this context.
* 앗! (at!) - A simple exclamation of surprise.
* 으악! (euak!) - A more exaggerated expression of surprise or fright.
For endearment:
* 야! (ya!) - A casual and friendly term of address, similar to "Hey!" or "Boo!"
* 애기야 (aegiya) - "Baby" or "Little one," often used affectionately.
* 자기야 (jag-iya) - "Honey" or "Darling," used in a romantic context.
You could also use the English word "boo" itself, especially when trying to recreate the playful tone:
* 부! (bu!) - This is a phonetic pronunciation of "boo."
The best way to express "boo" in Korean will depend on the specific situation and the relationship between the speakers.