Trying to get off work. Help.

So, next weekend, my cousin is having a wedding. We've been planning on going for a few months now. Last month, I took off for the weekend at my job, but when the schedule came out, they put me on for the schedule. My store manager said it might be because the college kids are coming back to school. I can't even get anyone to take my shift because EVERYONE except for one person is scheduled to work the whole weekend. I already asked that person if she could take my shift but she has a baby at home and can't really get a babysitter on the weekend which I understand. I plan on going to the wedding no matter what. I feel very angry because I'm always there for my manager when somebody doesn't show up for their shift which causes me to work 7-8 days straight and I'm the first person to volunteer to stay longer when someone from the next shift is coming a late. I always have my managers back when I can get to work. I've only declined twice which is for transportation issues. I just feel like if I'm there for them, they can be there for me. My mom said we can just stay for Friday and Saturday (I have off Friday) and I can call out Saturday, but I'd really like to stay for the whole weekend. She said I can fake sick, we came up with pink eye, which I can fake, because I can't come into my job (a restaurant) with pink eye. Any other ideas? Something believe-able?