sneak up to
sneak up to (someone or something)
To creep up to or alongside someone or something in a secretive or inconspicuous manner so as not to be seen or noticed. I snuck up to the window to see what was going on inside the building. She snuck up to the man and slipped a note into his bag.
sneak up to someone or something
to move close to someone or something quietly and in secret. I sneaked up to Don and scared him to death. Don sneaked up to the punch bowl and helped himself before the party began.