'Oops My Water Broke!'

That's the name of the game on Ellen.. and NBC's Justin Hartley tries it out with Rachel McAdams to raise money for breast cancer research.

The 'This Is Us' star strips down on the daytime show and reminisces with the host about that one time at the Daytime Emmys..

Watch Ellen weekdays at 4:00 on NBC 12 and 'This Is Us' Tuesday nights at 9:00.

'Oops! My Water Broke' with Rachel McAdams & Justin Hartley