Well this is embarassing for the gaming community at large.
Setting aside that your friend is a complete moron, perhaps he can be persuaded by a romantic appeal to sensibility.
That is, The game has already made indelible changes to his person - literally affecting his body. The game that he's played has inscribed complex lines of connection between neurons and synapses - done so by him playing it, experiencing its sights and sounds and interactions. As much as it means to him, he can expand upon the impact the game has on his spirit, by simply coming to understand more of the world and its creation.
On the other hand, eating a cartridge as a method of heightening one's relationship with the game is akin to heightening's one's relationship with food... by listening to it. Actually, probably worse - because at least with food, you can hear the sounds of it when you chew on it.