It means the same as the phrases, "you bet your ass" and, "you bet your dick and balls".
That is, you're absolutely, positively, 100% certain about the final outcome of a situation.
{Seen on a website about flashlights, LEDs, and lasers}:
I tried to cut through the outer casing to bare metal with the blade of a Swiss army knife, and with some minor difficulty, I was able to do so. This shows the unit has a Type II anodized finish to it (...)
Would I really cut up a brand spanken new $450.00 laser? You bet your sweet patootie I would, if it's in the name of science.
A mixed drink combining sweet tea and bourbon. Originally named after Dothan, Alabama. The tea's ability to mask most of the bourbon taste, but still leave some of the rich bourbon flavor makes it a must try for any truesoutherner.
"Do you know of any drinks named after towns that no one has ever heard of?"