I would love to, but...
1) I want to spend more time with my blender.
2) I'm teaching my ferret to yodel.
3) I'm going to my vanilla cheesecake withdrawal meeting.
4) My crayons have melted together!
5) I'm getting deported.
6) I'm attending the opening of my garage door.
7) The Queen said she might drop in.
8) I'm building the moon from a kit.
9) I'm emptying my sandbox and then filling it again with the same sand.
10) I have to sing with my pet flea, Thomas Henry III.
So, there are 10 ways that I like to say 'No!' and nobody ever asks me questions after that, they are usually pretty silent and quite stare-y actually to (But I don't know why, they are a bit weird).
(I bet you're wondering why you never thought of this sooner!)