Question:
Can I pierce my ears on chol hamoad sukkot?
Answer:
If the earrings are going to be put in to your ears on Chol Hamoed or on Yom tov then essentially it is permitted because it is "tzorech hamoed", and it may be done on Chol Hamoed. However if you waited to do it because chol hamoed is a "free" day etc. then it would not be permitted. The reason being because even if something is tzorech hamoed (for the benefit of yom tov), if he planned to do it specifically on chol hamoed (mechaven melachto b'moed) then it is not permitted.