You totally can and should. Being honest about not getting to something is better than covering it up. So long as its not a regular occurrence then it should be

You totally can and should. Being honest about not getting to something is better than covering it up. So long as its not a regular occurrence then it should be okay. And its even easier if you set expectations up front. "Hey im going to spend some time socializing with xyz today. I might not get to much sprint work"