"tell a white lie"
Meaning: say something that isn't true in order not to hurt or offend someone
Example: The spaghetti that Anna prepared did not taste good, but I knew that she put a lot of effort on it. That's why when she asked me if it was good, I just told a white lie and replied that it was, and I liked it.
Last week's idioms:
nosh
on the dot
plastic
a quick study
rain or shine