I was editing a program that I wrote maybe 10 years ago, for my own personal use, and have never touched since. While doing so, I found this comment:
/* Dear Steve-from-the-future, this is Steve-from-the-past.
You almost certainly think I messed up here and that the
code could be cleaned up with a trivial fix about 5 lines
down from here. Well don't! It’s like this for a reason!
Hope you're enjoying the flying cars and personal rocket packs. */
…I have no memory of ever writing that - but I heeded my own advice and left the code alone.