sneakily

/ˈsniːkəli/
adverb
  1. In a way that is secret, quiet, or dishonest, so that others do not notice or know what you are doing.
    • She sneakily took the last cookie when no one was looking.
    • The cat sneakily crept up on the mouse.
    • He sneakily copied his friend's answers during the test.
Antonyms