I am amused by writing prompts that tell you what they’re not interested in hearing about. “Please write 500 words, not about X, but about Y.” They always make me want to write either:
a) Theory of X
b) else about something entirely other than both.
The best writing prompt is “Tell us something that will surprise us.” Or: “Tell us something interesting.” Or, better yet, “Tell me something I don’t know.”