Is it possible to spend more than you have at the bank without an overdraft agreement?

Yes, it is possible to spend more than you have in your bank account without an overdraft agreement, but it typically results in declined transactions or bounced checks. Most banks will not allow transactions that exceed your balance, but in some cases, merchants may process a payment that leads to a negative balance. If that happens, you could incur fees for insufficient funds. Always check your bank's policies for specific details.