What do you do when you slip up?

I don't consider it a slip up, it's just life. Life is not always predictable and plannable, so learning to be flexible is important. Hungry? I either wait it out or eat more. If I eat more, then that's that, if I'm not hungry next day I just don't continue eating more, and problem solved.

Any extra calories can be safely ignored if I get back to what I was doing and don't continue overeating. If I'm not very hungry and feel like making up for overeating, I just eat less the next few days provided it doesn't feel like punishment. If I notice myself feeling hungry and doing negative "serves you right for overeating" self talk, I halt my compensation plans immediately and move on. Not every calorie needs to be made up for.

For things that can be planned, like a day out or a party, I just eat a little bit less/move a little bit more that week to bank calories for the event.

If I want a couple too many wines (well, other things in my case because I don't like wine), I plan for them in advance. This happens like this:

1. I decide what I want to have and if it's worth it. Example: "This weekend I'm going to have a large bag of chips, not a single serving, and I understand that I will have to work for that. I haven't had chips in a while, and I feel this is worth it."
2. I calculate how much it would cost me. "A large bag of chips has 800 calories".
3. I decide how I'm going to split those calories depending on my appetite and what I feel like doing. Some of my usual options are: having one very low calorie day that week (800 calories fewer than my usual budget), doing 100 calories fewer every day for 8 days, doing 50 calories fewer but exercising for 50 calories more for 8 days, or any size deficit/exercise that feels right to me that week. I may also decide that I'm fine with a smaller deficit that week and understand that it will mean slightly slower loss, in which case I don't do anything differently and eat my chips anyway.