Honestly, a Modulo-Captcha wouldn’t be that bad of an idea?

Sure, it’s not really “non-dev-proof”; but I guess a simple “To enable pasting, please type result to the following formula: 5%3” would at least stop some people that will glady ignore the warning because obviously nobody wants to let you hack other Facebook accounts, but those guys told me it’s fine - but will already be confused and then feel smart by entering 0.15 because 5% of 3 is 0.15 … and wonder why it doesn’t work