slip back (to someone or something)
to move quietly and cautiously back to someone or something. Walter slipped back to Sally when her parents weren't looking. He slipped back and then Mary's parents slipped back, and there was quite a scene.
slip something back
1. to pull or place something back. Alice slipped the gearshift lever back and away they went. She slipped back the gearshift and sped away.
2. to return something secretively. Someone took my wallet away and slipped it back later. The thief slipped back my wallet, but the money was gone.