Trying to imagine how, and the only thing I can think of is that technically you can write a contract on anything? And possibly a cheque, too, because a the cheques in a chequebook are just a standardised IOU form with exactly the same legal weight as if it was done by hand?
(Vague memory that someone used this to avoid paying a bill, because refusing a cheque when offered counted as discharging the debt it represents (if I have the right terminology), and as cheques could be written on anything they chose to write it on a car that physically would not fit through the door).
In this thread's context, the "constitution" is the kind of thing which is supposed to make that not happen.
Famously bereft of a written constitution, the closest single document along these lines which the UK had for a long time was ("the") Magna Carta, which basically exists because King John's lords were tired of King John directing the courts that King John personally owned to not hear cases against himself.
But if your point is that some constitutions may as well be toilet paper for how much the people with power care about their contents, then I agree.
Famously, the toilet paper known as the US Constitution has prevented any violations of rights recently, like the brown skinned people getting brought to concentration camps, or your dog getting shot because you used free speech.
