behind (someone's) back

if you do something behind someone's back, you do it without them knowing, in a way which is unfair.

I don't want to talk about it behind his back.

She was accused of going behind her colleagues' backs to talk to management.

• cut someone loose
• cut someone some slack
• cut someone to the quick
• cut some slack
• cut something down to size
• cut something loose
• cut teeth
• cut teeth in
• cut teeth in something
• cut the cord
• cut the crap
• Cut the crap!
• cut the Gordian knot
• cut the ground from under feet
• cut the ground from under someone feet
• cut the ground from under someone's feet
• cut the umbilical cord
• cut things fine
• cut through
• cut through like a hot knife through butter
• cut through like a knife through butter
• cut through something
• cut through something like a hot knife through butter
• cut through something like a knife through butter
• cut to the chase