Have a day.
Good or bad is up to you.
I wouldn't presume.
If you are trying to get away from the tiresome returns that everyone uses (How are you? Fine. What's new? Same old thing. etc...) Try mixing up the days. Someone says: "How are you?" Tell them "Friday" when it's Monday. I try to come up with different returns.
Oh come on now. I don't mind if someone tells me they hope I have "a good day". I'll take offense if they tell me to get fucked. I certainly don't mind someone wishing me the best. Be well.