My date of birth is the 1st of January 1901. My phone number is 0000000000. My gender is decided on a coin flip. My country of residence is Afghanistan. And my Mother's maiden name is a random mix of upper-case, lower-case, numbers, and symbols.
Well, that's what you would believe if you were any website I've registered for. If you're a free WiFi provider, you get random details. Unless you have a legitimate reason for needing my name and address, you'll find that I live in a desirable area of SW1A 1AA.
You have a moral imperative to lie. The people who want your details are going to abuse your data. And that hurts you and the people around you. Targeted adverts are used to make you buy things you don't want and to believe things which aren't true. Deep data collection is used to work out what sort of person you are, the lifestyle you lead, and the risks you take.
Even if you think you are totally immune to advertising (you're not) and that you have nothing to hide (you do) - mass data collection is used to target people like you.
It is vital that you add as much statistical "noise" to the data collection pool as possible. This helps protect everyone.
Giving fake details is a position supported by security professionals.
3. My favourite pet is “the Eiffel Tower”
Enter the minimum amount of authentic information into online registration forms. Do you really need to enter genuine information in every field if there’s no legal reason to do so?
My Digital Footprint - Centre for the Protection of National Infrastructure
This isn't a theoretical concern. Earlier this year, Network Rail's WiFi provider exposed the details of people who'd registered for their free WiFi.
You should only fill in the mandatory details on a website
You should use an Ad Blocker as regularly as you'd use a condom - and for much the same reason.
If you have the patience, get a disposable SIM card and use that for receiving calls and texts from businesses or marketing firms. Then replace it after a few months.
To be clear - don't lie to people who have a legal right or legitimate need to know your details. Lying about your address to a delivery company means you won't get your parcel, and lying to your doctor could result in harm. Don't even think of deceiving the taxman.
But if someone you have no reason to trust asks for your data - feed them garbage.