Get 4-5 pillowcases and stuff them with heavy items so that they weigh a good 15-20 pounds. You can use anything heavy that will fit, heavy books or bags of rice or beans work very well. Divide your guests into groups of 4 each and create racing lanes for them to have a relay. In each lane drop 4 baby objects like bottles, pacifiers and bibs randomly from start to finish.
Each team will gather at one end of their racing lane. Tie a filled pillowcase around the waist of the person who will start for each team. The objective of the game is for each team member to tie the pillowcase around his or her waist, run down the lane and on the way back, bend and pick up one item. When back at the start the first person will then pass the pillowcase to the second team member who will tie it on and run down the racing lane, picking up one item on the way back. All team members must take a turn until all the items have been cleared off the floor. The team that collects all the baby items first wins.
While running with the extra 15 pounds may not be so difficult (especially since the guests wont be worried about hurting the books!), bending is going to be tougher than they imagined. This game can be a little bit of a workout so make sure your guests are up to the extra weight and action.