Which is more rude?

[Theophany]

Still don't understand this office "bringing food in for everyone else" thing

I just say thanks for the offer.
I'm not bringing anything in, I won't bother so I don't feel obligated to.

Very different culture than what I have worked in previously.

I don't get bringing in food either. When I worked at an investment bank we used to bring in lines of coke for each other - and it was considered a major faux pas to decline that offer before playing with a few million in government money - but cake? Seriously?