Caffeine is especially interesting, as it is commonly consumed and there are incidents where people are hospitalized because they accidentally ate too much - https://pmc.ncbi.nlm.nih.gov/articles/PMC8824417/ (referencing the 6000 mg here)

> * Caffeine powder (another game of guess the dosage)

I found a study saying "the caffeine content in tested dietary supplements is 4–35% higher than the declared amount in most cases" which doesn't seem very dangerous.

You can overdose on caffeine in other ways, of course.