Have a race, making the men drink punch/beer/whatever out of a bottle.
Hang baby clothes on a clothesline while holding a toy baby AND talking on the phone.
Have the men race (just because it's funnier to watch the men squirm), to undress the toy doll, change it's diaper, then get the doll dressed again.
Or do like a '3-armed-race' where the couple has to hold hands (just one hand each) and change the baby's diaper together. Say something like "Since we all know that when babies come, you gotta work hard to keep the marriage strong, in this exercise you will stay connected holding hands but take care of your baby's needs as well." They could either change a dolls diaper together OR fold onesies, socks, towels, etc, OR mix and measure formula (use fake stuff, koolaid/sugar maybe instead since it's cheaper) and put it into a bottle.