Idioms ESL-Lab, 2022-09-22

[Easy - Holiday Traditions]

• sneak (verb): to advance or approach without being seen (살금살금 몰래 가다)
  – My son often tries to sneak into the kitchen and take a cookie when no one is watching.
• sneak up (on somebody/something) : ~에게 살금살금[몰래] 다가가다

  - He sneaked up on his sister and shouted ‘Boo!’.