I think their memory will do it for them without you stooping to their level?
Usually when it happens, they already look pretty embarrassed.
A shrug from me is all it takes to acknowledge the fact.
Anything more is probably overkill.
Why do you have to tell this person “I told you so”? The next time it is you who is being reminded that you were told, could you just ask this person not to do it? Aside from annoying this individual and possibly giving them a taste of their own medicine, what do you hope to accomplish?
There is no nice way to do it. Since you know that you told them, let that be enough for you.
Focus instead on having a bit of compassion for them. I am sure that you have made mistakes or done things that people told you were not a good idea. Sometimes we just have to find out for ourselves.
You know what’s ironic a episode of office was on today and it’s the one where a corporate lady wants to fire one of the employees from
The office and michael doesn’t want her too. Long story short the corporate lady’s boss yells at her for wanting her to fire the employee and michael asks “how do to tell someone I told you so nicely, with a cup of sugar, a bag of candy, a hug???”