Pint-sized means very small, and people almost always say it with a smile. You use it of a child, a pet, a car, a house — something whose smallness feels surprising or sweet. A pint is a smallish measure of beer or milk, so the picture is: no bigger than that glass. It is informal. A newspaper might call a compact car pint-sized; a parent might call a toddler pint-sized. It is not a serious measuring word, and it is too cute for a science report. Though actually, it does not mean “as small as a toy.” It means smaller than you expected, in an everyday, human way. About a child or a puppy it usually sounds fond. Do not use it of a stranger’s body; there it can sting.