I/I'll tell you what

tell you what

A phrase indicating that the speaker is going to present a suggestion or their opinion on something. I tell you what, this burger might be the best I've ever had. Tell you what, why don't you go out for a run and I'll watch the kids for a while. I'll tell you what, that was some concert.
See also: tell, what
Farlex Dictionary of Idioms.

I/I’ll ˌtell you ˈwhat

,

ˌI know ˈwhat

(spoken) said before making a suggestion: I tell you what — let’s ask Fred to lend us his car. I know what! Why don’t you buy her a CD?
See also: tell, what
Farlex Partner Idioms Dictionary
See also:
  • tell you what
  • I tell you
  • (as) sure as eggs (is eggs)
  • beck and call
  • going, going, gone
  • going, going, gone!
  • how about
  • how/what about...?
  • eggs is eggs
  • (one's) best foot forward