I'm not going to my grandfather's funeral
Why aren't you going to his funeral?
I'm too busy to attend such a meaningless event.
You're expected to go to the funeral of close family, like your grandfather. Your family would be really sad if you weren't there.
Maybe I will go to the funeral, introduce the whole family to my new chick and fuck the shit out of her.
That is an incredibly inappropriate way to behave. While you might not care for your grandfather, other people in your family will see this event as an important event to honor his life. You shouldn't think about having sex while other people are grieving.