to not talk about things which have caused problems in the past, or to not try to change a situation because you might cause problems.

His parents never referred to the shoplifting incident again. I suppose they thought it best to let sleeping dogs lie.

It wasn't that we didn't want to improve the school - it was more a case of letting sleeping dogs lie.

• make a noise about something
• make a ... of it
• make a pass at
• make a pass at someone
• make a pig of
• make a pig of yourself
• make a pig's ear of
• make a pig's ear of doing something
• make a pig's ear of something
• make a pitch for
• make a pitch for something
• make a play for
• make a play for someone
• make a play for something
• make a point of
• make a point of doing something
• make a poor fist of
• make a poor fist of doing something
• make a poor fist of something
• make a practice of
• make a practice of doing something
• make a production of
• make a production of something
• make a production out of
• make a production out of something