Asking for money to babysit?

My sister has been working a lot and wants to go on a date with her boyfriend who she hasn't seen in 6 months. She asked me to babysit. I said I would get back to her. My sister's kids have 0 discipline. She lets her kids do whatever they want. They scream, break thing, cuss at you. They're 13, 12, and 10. Her 13 year old daughter went and tortured my car until my cat finally attacked her. They have busted out my windows in the past and the last time they were over here her daughter took a bat to my TV. My sister doesn't discipline. She says she doesn't have time to worry about her kids. Weird thing... When they're with her ex and his family they don't act like that.... But she's fighting with him rn and didn't want to ask.... I get she wants a break but would I be awful to ask for money?