why can't I say no

I just came off a 10 day vacation. I was sick for most of it and got nothing done. I never feel like I have enough vacation time. This year I will start with 24 days which includes 4 floating holidays. So.........my friend calls and asks if I want to go to Las Vegas; he's buying the plan ticket.
I tell him no, it's right after the holidays, don't really have any money....yada, yada, yada.
So Sunday I check airfare and call him. Since I am staring a new job Monday (different department), I will ask. New boss says sure. So on Jan. 3rd, we plan a trip to Las Vegas for the 13th...as in 10 days away.
I ask Dina what am I doing? I just had a vacation...money is tight, I feel overwhelmed in my new job----yes, after one day--and all I want to do is run to Las Vegas with Robert. She says you're single, do it!

So my 1st day, I have 2 court appearances on cases I know nothing about. So the old worker goes with me and gets into a fight with an attorney on the 1st one. And we get custody of a child on the second case, who is supposed to be moved Thursday. Did I mention they have me in training Tues and Wed? No one has told me what needs to be done and the supervisor was out of the office. By the way, I didn't have a phone at that point, and the old worker tells me I have to submit certain paperwork within 24 hours.
Soooooooo, today, we are in training. Come down for lunch and the phone is working, but there is voicemail on it and can;t get it because it's the old worker's pin. SoI call the phone guy and find out what to do. Ok, there's 17 messages. The supervisor asks me how I got to the messagees since we couldn't earlier, I tell her I called the phone guy. She is happy, likes that I take initiative.
Meanwhile service providers have scheduled meetings and clients are calling and I know NOTHING. I think I have a meeting every day in the next 2 weeks, with a vacation thrown in....baptism by fire.....where's my wine? I'm also tired of people asking how I like my new job.