Sirius was distracted by actually listening (or trying to) and stumbled backward when he was pushed. "So. Huh. A mini-Moony? Neat." He shoved James, still half-distracted. The idea of a girl Moony was interesting, especially after what Moony told him last night. Not that Sirius was interested in teenagers. Okay, not that Sirius would act on being interested in teenagers. Especially not James' niece-daughter-person.
"Was just getting used to the idea of you having an infant, mate. You're trying to blow up my brain, aren't you?" He rammed his shoulder into James' chest. "Yeah, sure, I'll meet her."