Hilary Duff and Co-Star: Oh, Baby!

No, Hilary Duff and her hockey-layer beau Mike Comrie haven’t somehow spawned on the sly. The tot that the former Lizzie McGuire actress was romping with in New York yesterday was her co-star.

Duff was filming her upcoming guest stint on Law & Order: Special Victims Unit.

But Duff sure does look like a natural frolicking with the little tyke in an uptown playground, doesn’t she?

In her guest appearance, Duff plays a young mother accused of murdering her baby.

So, spoiler alert: Don’t get used to the kid.