As far as dollar amount, probably some meal with my girlfriend. We don't do fancy but usually have one nice meal on a vacation.
But as a percentage of my income - something called Bonzai Chicken I ordered for $70 on my honeymoon back in the 90s. I made $7/hr at the time. I didn't know it had curry in it or that I was allergic to curry. I spent the remainder of my honeymoon sick as a dog.
That sounds like an 80s movie plot though. Half the movie was you on the toilet while everyone else got up to some epic shit. All because you had to order the Bonzai Chicken.