Nope. Ignoring or refusing to answer the question is grounds for denying admission or being permanently denied admission.

You can just say "no". And smile. Will be completely correct on your part.

> Guard: "Have you consumed weed in the last 30 days?"

> You: "No"

If you have consumed in the last 30 days, then your "No" response is definitely not correct.

Yes it is correct. They have no business asking this. If a question is incorrect, you can answer whatever you like to it.

Lying is only giving wrong answers on correct questions. If a person sticks their nose where it does not belong, too bad.

I have rights to do any kinds of thingd to my body, and I have exactly zero obligation to disclose it, unless in strict contexts of medical help or driving.

I don't understand your "teach you to think before talking" remark. I said your comment was orthogonal because it didn't address anything I had said in my other comment. Of course someone wanting to the enter the country will weigh their options, I'm just laying out the potential consequences, for someone that apparently had not heard of them (the other commenter, not you).