The staff goes to a baseball game

Next Thursday, all my coworkers and I are going to a baseball game. We're not playing in the game, and no one we know is playing in the game... we're going to a professional baseball game. It's not that I don't like baseball... I like playing and I liked going to games when I was a high school teacher and the kids I actually knew were playing in the game, so I actually cared if they did well. I don't care about professional baseball and I haven't been to a professional baseball game since I was a child. My family used to go to Dodger games; the only things I remember are the name "Steve Garvey" and playing with a long red licorice rope the whole time, and being smeared with sunscreen by my mother at intermittent intervals.

Since I am fairly new on staff I don't know whether this decision to go on an outing was made before I landed there... I remember some discussion about what days were best for everyone. I'm a bit envious of my coworker who is off in Greece for a few weeks, not just because she's in Greece but because she gets to miss the game! Following the game is a barbeque at my boss' house. She has her good attributes, but she's a sarcastic, frequently high strung, more than occasionally micromanaging, self-described bitch. Yes, she's one of these people who revels in calling herself a bitch, and in embodying that state of being.

I could call in sick, but I've had a cold for a week and I called in sick last Tuesday and again this Monday, and another sick day would be excessive (and suspicious). I could also take a knitting project with me to the game, because everyone knows you can knit and watch TV or knit and talk, and presumably knit and watch a baseball game, but what about the barbeque? I could eat a hotdog early on in the day, not feel well, and leave with a stomachache (only to go to a nearby salon that I like a lot and get a manicure and pedicure!)... I'm a terrible actor and an unconvincing liar... just planning the ruse would give me a real stomachache. We're expected to RSVP for the barbeque today (she sent the invitation late yesterday)... what do I do?