Risks with 1 day overstay

Hey,

I'm going to Bangkok 8th september and leaving 7th december, which is 91 days.

I'm from Norway so I have 60 days "free" and then I have to extend with 30 days, which gives me 90 days total.

Someone told me that they don't really care and that I probably just have to pay a small fine when leaving, but I'm just wondering if anyone can confirm that?

I really don't want it to be a problem before entering the country/at the airport which is why I'm asking.