(Author's Note: Hikaru's version of this episode is technically a continuity error, since Buffy is wearing a sling bikini, instead of a normal one.)
The baby, easily visible as a boy because it wasn't wearing anything, sat on Buffy's lap and looked puzzled. He cried out of hunger and looked around for a food source. Buffy's breasts were there just above it and they were getting full of milk too fast, but they were covered by the blue bikini.
The baby tugged at the bikini and Buffy finally said "Don't poke me! You're being a pest." He just tugged again and Buffy replied "Oh, fine." She pulled one of the bikini straps to the side so that the baby could get to her breast.
Buffy's hungry baby went for Buffy's nipple, sucking the milk out happily. And although Buffy held some motherly love for her newborn child, she rather would have been doing something other than breastfeeding at that moment.