Yeah, but he told me he puts the butter on the inside.
As a point of order, no, I did not. I said 'at least on the bottom slice' without any recommendation as to inside or out.
But, that being said, if it weren't for grilling, then yes, butter goes on the inside of the bottom slice , to keep the juices from being absorbed by the bread... So they can be correctly deposited upon one's t-shirt, as is proper.