Laawsht it - You think you're the best, but you end up being the worst in

You think you're the best, but you end up being the worst in a really loud way.

I thought I'd nail the presentation, but I forgot my notes and talked nonsense.

I was sure I'd win the race, but I tripped and fell right at the finish line.

I told my friends I'd cook, but I burnt everything and it smelled like a fire.