What backpack is a must?

My boyfriend if obsessed with backpacks. We made a bet that he will not buy another backpacks in the year of 2025. I placed 200eur on him that he will break. He said he will not-it is all one big joke but he can be quite stubborn when he dicides. Now i have to come up with a master plan, which backpack he could not refuse. He already has about 15, just in January he bought 2... So please help me win the bet! He likes the backpack to take his lunch in office. It needs to be wide enough for his glass tupperware. He has one Kapten and son backpack, well he has 2 or 3 models. One he likes a lot since the lower part in a zipper and fits his lunch in perfectly. He also has a few sports kinds... I would be grateful for your suggestions