I must say

I must say

Used to introduce and emphasize one's opinion. I must say, Mrs. Robinson, you are looking exceptionally gorgeous this evening. If that is his explanation, then, I must say, that's the stupidest thing I've ever heard.
See also: must, say
Farlex Dictionary of Idioms.

I ˈmust say

(spoken) used to emphasize an opinion: Well, I must say, that’s the funniest thing I’ve heard all week.
See also: must, say
Farlex Partner Idioms Dictionary
See also:
  • take the words out of (one's) mouth
  • take the words out of mouth
  • take the words out of somebody's mouth
  • take the words out of someone's mouth
  • took the words right out of my mouth
  • going, going, gone
  • going, going, gone!
  • flatter
  • flatter (one's) figure
  • flatter figure