Arrrgh! Why can't H remember something 24 hours later?!

H has been working OT for the past couple of weeks. He hasn't worked the weekends but has been working an extra 2-4 hours a day. I told him a month ago about our Christmas Party which he said he couldn't wait for. I told him again about it last Thursday when we got the details on it. I told him on Monday night that I signed us up. Each of these times I told him it was on Friday Dec. 12. He went "This is going to be an awesome time". I said "It WILL be fun. Just be sure not to work OT that Friday or that weekend". He said "You got it". Last night when I get home he tells me that he's not working this weekend but next weekend for sure. I sighed and told him "I told you not to work next weekend because we will be out late on Friday for the party." He goes "Uh oh". I said "Is it mandatory that you work next weekend?" and he said "Pretty much." They can't MAKE you work a weekend! Just tell them something else came up. He says "Oh I'll just take it easy at the party.If we are home by 11PM I'll just have to sleep fast and be up by 2AM and suck it up" No you won't! You NEVER take it easy at parties. You can't help yourself but drink.Plus there is no way you are going to be up 3 hours later. Just tell them now you can't make it. I don't want this party to be ruined by you wanting to leave early or getting upset that we are out too long. We'll be on a boat for the last 3 hours of it so there's no leaving that!