play dumb (?.)

• be mute
• be silent
• bosom
• classify
• conceal
• file and forget
• forswear speech
• hold out on
• in petto
• keep
• keep back
• keep between us
• keep buttoned up
• keep close
• keep dark
• keep from
• keep in ignorance
• keep mum
• keep quiet
• keep secret
• keep silent
• keep snug
• keep still
• keep under wraps
• make no sign
• never let on
• not give away
• not tell
• say nothing
• secrete
• shut up
• stand mute
• veil
• withhold