let something slip
give the game away
slip
let slip
out with it
secret of Polichinelle
tip one's hand
skeleton in the closet
resecrete
skeleton in the cupboard
something nasty in the woodshed
on the hush
off-the-record
keep a lid on
mis-
out
stitch-up
disembosom
let the cat out of the bag
roll
spill the beans
make known
secretively
covert
exposure
yield up
divulgence
misrelease
mitch
divulgement
on the down-low
under the covers
closehanded
underhanded
secretly
semisecretive
under the rose
divulgation
secret
furtive
underplot
latently
anecdote
keep from
accidently
subdititious
babble
fredaine
tumble on
bechance