This is exactly what I do. Lying is my #1 pet peeve. Everyone in SO's family knows that during football season he doesn't leave the house on Sunday. I prefer to stay home too but if my team isn't playing and it's something I would like to go to I will make an exception. His family still plans things on a Sunday and we will tell them "Sorry but that's football Sunday." At first we got the flinching and hesitation and the "you're joking right" but now they just know. And since the other men in the family refuse to come they don't do things on Sunday now. lol They are having a bday party for one of the kids this Sunday but the Eagles play Saturday so I can make it. And I have been known to tell someone "I'm just tired and want to sit on my couch and do nothing today." I have a December birthday. I've never as an adult planned ANYTHING for my birthday. No one likes to go out in the cold, no one wants to spend extra money in December, everyone's calendars are full. So I just do something with my SO and kids. Sometimes, as a group, we decide something last minute and just hit a bar but that's about it. I have thought about celebrating in June!