Lucky me, I got this lovely circle of rust as a reminder of what I did. (And I know my photography is crap-tapulous, so it doesn't look too bad, but I'll tell you, it was a doozy. It's there at the bottom in all its orange glory.)
The solution to this problem? Vinegar. Just plain old vinegar. I poured it on the spot and let it sit for 10 minutes or so, then rubbed it a little with a paper towel. That was it, and I did it all while holding Little Guy #2 (to be fair, nearly everything I've done for the past 5 1/2 months has been with one arm while holding him).
And, turns out, vinegar expires. Looks like mine did about 5 years ago. Yep, 2004 baby. (Don't worry-I'm not poisoning my family or making weak Easter eggs-this jug is from my cleaning supply bin, not the kitchen.)
Now here's my "after". I know it looks the same as the before (again, phenomenal photography), but trust me, it's about a million percent better (rough estimate only).
So this might not be a mind-blowing bit of information, but you may need one day when you're a genius like me and leave a can in the sink to get wet and rust.