I was "살짝콩" shocked since Tim didn't know about this. lol
살짝콩 is actually not a correct word.
But I guess they used this in order to make the sound cuter.
살짝쿵 <- 살짝꿍(a dialect from North Korea for '살짝궁')
살짝궁 is an emphasized version of 살짝
살짝 means... (you can find in the dictionary though)
1. furtively/by stealth/in secret/on the sly
2. effortlessly/easily
3. softly/lightly/slightly/gently
Hope this helps.
Sean