1. What does it mean?
떡상 is emphatic slang for something shooting upward. It can describe a price surge, rapidly growing video views, an artist's popularity, or any striking improvement in a metric.
Also written or said as tteoksang
2. The nuance
It has no fixed numerical threshold and can be exaggerated. In market talk it describes or hopes for a rise; it is not evidence that further gains will follow.
3. Examples
“짧은 영상 하나로 채널 조회수가 떡상했어.”
One short video sent the channel's views soaring.
“떡상이라는 제목만 보고 내용을 판단하지는 마.”
Don't judge the situation just from a headline saying it skyrocketed.
Sources
Sinjoeo Korean Slang Dictionary
References support the meaning and usage. Example sentences are written for NoCapWiki.