You use 'You bet' or 'you bet your life' to say yes in an emphatic way or to emphasize a reply or statement. [informal, spoken, emphasis] ⇒ 'It's settled, then?'—'You bet.' ⇒ 'Are you afraid of snakes?'—'You bet your life I'm afraid of snakes.'
They're allowed to run in and out like mice, you bet they are, dragging the goodies away.Weldon, Fay SPLITTINGWhat'll you bet that Catriona gets a mysteryplot out of this?MacLeod, Charlotte SOMETHING IN THE WATERHe says, this is a charming little house, well you bet it is, you didn't expect it to be a bunch of flowers, did you?Richard Francis PROSPECT HILL