How bad will it be to miss a full day of school without an excused absence?

Not very bad, unless you've already missed a boatload of school.

If you're talking about taking a quick road trip to Disneyland with the family, I'd say, "the only life worth living is the one wherein we truly live." Life and time are fleeting - enjoy it for what is offered.

Not bad at all. I had perfect attendance and I really don't know what had gotten into me so I just missed four days. I didn't have much work to do. I also had no excuse. You get 15 days of missing school every year with no excuse.

well the school will question why you're not there, so if you're talking about skiving when you get to school, you won't get away with it. usually in schools nowadays, if you are not in the first lesson they call home. my idea would to fake being sick, or get on to your parents phone and send a text or email saying you won't be at school, etc. if you're just asking how bad it is, then it really depends on why you are missing school. and if it is not with an excused absence they will usually call your home to find out why you are not at school.