you'd better believe it

you('d) better believe it

Absolutely, without question; rest assured. A: "Man, he's the fastest runner this school has ever had!" B: "Yep, you'd better believe it!" A: "And is the movie really scary?" B: "You better believe it!"
See also: believe, better

you'd better believe it

Also, you better believe it. You may be assured, as in You walk ten miles every day?-You'd better believe it! This imperative is almost synonymous with you bet your ass. [Colloquial; mid-1800s]
See also: believe, better
References in periodicals archive ?
Well, you'd better believe it, because New Line is currently making offers to directors on the strength of Depp's interest in portraying the late flamboyant pianist known as Mr.