I don’t know what kind of place you work at, but say something demented that will scare her off. Like you plan on sewing shut the eyes and mouths of neighborhood strays as a way to practice on eventual humans
I really can’t say… I signed a non-disclosure agreement and the CIA is pretty strict about that kind of thing.
Are these actions simultaneous, or sequential? Think about your answer, it’s important to the rest of us.
And to the OP, I picture your office nosy-parker as the lady from Office Space who says “Looks like someones got a case of the Mondays”
Put me in the camp with those who don’t get why this is such a big deal. I often do nothing on the weekends and have no plans for major holidays, and I’m not the least bit offended if someone asks what I’m going to do, nor distressed to let the asker know that I’ve got nothing planned.
I smile broadly and let them know that doing nothing is exactly how I want to spend my weekend. If someone asks Monday morning how my weekend was and I’ve had my usual action packed weekend of napping, reading and hanging out with my dogs, I tell them that and add, “it was awesome”
I ask my coworkers about their weekends because it is appropriate small talk. Like mentioning the weather. I can’t imagine anyone really caring all that deeply about how that question gets answered.
I can’t tell you because it requires a security clearance and a need to know. But imagine James Bond, and what he does when he isn’t working. Or maybe I will be working.
Care to come over and watch me do nothing all weekend?
“A little this. A little that.”
The screen keyboards on tablet computers make one-handed typing much more natural …
I’m one of those who doesn’t do much on the weekends but relax, watch TV or play on the computer. I would tell her either “not much” or “the usual” and ask her how her weekend was or just deflect and immediately ask about her as some others have suggested. If she gets huffy or judgmental, I would then ask her not to pass judgement or that she’s not my mother as politely as I can.
Are you pondering what I’m pondering?
“You never have plans for the weekend.”
(Steeples fingers and drums fingerpads together while smiling evilly) “Yeessss. My plan is working.”
It just sounds to me like you are getting offended over an innocuous comment. This sounds more like social anxiety. I know, I experience it a lot now that I’ve been out of the loop for a while. You scrutinize everything.
It is far more likely that she didn’t mean anything other than making an observation, and that no problem is going to develop because of this. What you said before is going to work again. There is no reason to interpret this as her scrutinizing you. Most people don’t do that. And, even those who do don’t do it on something so banal.
Especially since you said she also never has any plans. Yeah, there are some hypocrites out there, but that’s some pretty bad hypocrisy.
As for my advice? The time’s already past, but the perfect response would have been, “That’s the way I like it!” delivered cheerfully. Then maybe followed by an explanation, such as “I love having that time just for myself.” or “I’m not really a planner,” if that’s more accurate.
Now, honestly, I don’t think you’ll get much of a chance to say anything clarifying that you don’t like having plans unless you just bring it up yourself. When she asks about your plans, say something like “I just love doing nothing on the weekends. You?”
Or you can keep with the earlier advice in the thread. It doesn’t really matter. In fact, that’s the point. This is all just idle chit-chat, and none of it really has to matter. Take it in the spirit offered. Chances are quite small that she’s judging you, and, if she is, so what?
See, what you describe is very different from the OP. You work with some rather rude people, in my opinion. I can’t imagine being with people like that. You have my sympathies.
You might indeed need to do something to let them know that you don’t appreciate that type of questioning. Unfortunately, I’m completely out of my element here. I’ve just literally never had to deal with anyone like that. I can only think it’s some sort of cultural difference.
Yeah, sure, a single, jovial comment might make sense, being some sort of “Yeah, that’s our monstro. She’s boring, but we love her anyways”-type thing. But what you describe is ridiculous.
I think so, Yllaria, but if they called them sad meals, kids wouldn’t buy them. 
I’m a woman who leans towards the youngish side in the age structure of my workplace. That means people readily assume I am in need of unsolicited advice and intervention. My physical appearance, my diet, my social life…all of these are topics up for discussion. And I have to skirt carefully with my responses, lest I come across as “taking things too personally”.
Sometimes I really wish I was a guy.
She wants you to help her move furniture. If she ask you what your plans are and you say “Nothing special” then she’ll say, “Good, come over and help me move furniture.”
At least that’s what my sister did to me. Damn sisters. 
I used to say I shot a man in reno, just to watch him die. But, with current news events, I’ll have to find another flippant answer.
Lately I’ve been saying “Time Tripping. Billy says hi.”
Just tell her that if she wants to engage in idle prattle about your life, then she better just sign up on SDMB, where you are happy to engage in such discussion including even more serious conversation, where you feel safe behind your firewall and monitor. But that face to face banter, for some reason makes you feel threatened.
I also like for my weekends to be pretty low-key (one social event per weekend is definitely enough for me, and often I prefer about one every other weekend so I have some weekends to myself to just relax and do chores). Just say something generic, “oh, not much, relaxed, ran some errands, caught up on chores around the house, visited with some friends (even if it is just by phone/text/online), how about you?” I agree it was rude for her to say “you never do anything on the weekends!” in a judgmental way.
Add goat leggings and methyl alcohol and we’re practically twins.
smile, giggle and say “oh nothing, you?”
that way you’re not really saying anything to her and she’s too curious about your weekend to harp on about her own
Now this is the one that will work! 
But if you are wanting to keep things civil… Annamika’s is a good one
**So I resort to, “Oh, nothing much, how about you?” And try to ignore it. And if my coworker ever said to me, “You never have plans for the weekend,” I’d smile and say, “Actually, I just rarely talk about them here at work. They’re not all that interesting, anyway.” And shrug. And wild horses wouldn’t be able to drag anything further out of me. **