Dear Random Lady,
My three month old neither wants nor needs kisses from your toddler. I'm sure in your eyes, your child is the shit, but that doesn't mean I want his germy mouth on my baby.
Since we've never been introduced or had even a cursory conversation (and you didn't bother to ask my or my baby's name before instructing your son to kiss him), let me tell you something about our family: we believe in bodily autonomy. We don't believe in forcing kisses and we sure as shit don't believe in kissing strangers to appease their parents' sense of what would be really cute to see.
As mothers of boys, I think it's especially important that we teach them about consent from the get-go. That doesn't mean we have to discuss sex with toddlers, but it does mean that we probably shouldn't be instructing them to show physical affection to strangers with no regard for the strangers themselves.
Luckily for you, your son showed better judgement than you did and was about as interested in giving kisses as mine was in getting them. That saved us both from making an awkward scene at another kid's birthday party. Bully for us.
Neither of our children are dolls. They're not there for you to play pretend with. If you want to make things kiss for your own amusement, go buy some Barbies and leave my baby out of it.
My three month old can't speak for himself. It's my job to be his voice until he has one of his own. So on his behalf, let me just say:
Kindly back the fuck up.