I recall making such resolves before (and not sticking to it), but I'm going to try once more.
On several occasions, I've let people get away with being snarky and nasty to me, either because I felt any more nastiness on my part would be futile, or because I didn't deem them important enough to retaliate, or because they were too important to me, and hence I didn't take the nastiness along with its implied mean-ness, just let it slide as a good friend having a bad day.
Not a good policy in any case. So from now on, I'm going to return snark for snark, nastiness for nastiness, immaturity for immaturity. Let's see how that goes.