Jennifer is seven months pregnant; Balki and Mary Anne have been on their honeymoon for five months in Mypos and their about to come home. When they arrive, they have a surprise, Mary Anne is also pregnant but isn't going through any bad symptoms like Jennifer is. Balki brought a root back from Mypos that could help Jennifer but when Larry and Balki eat it, they start acting very hyper and ruin the baby shower.

Larry wants to put some sparks back in his marriage, and after he fails with Balki's secret treasures, he goes shopping with Balki and accidentally gets locked in the store after hours with a mad dog on the loose.

When all of Balki's ants on his farm die, he discovers that he has the "exterminiki curse" and everything he touches will instantly die. So he must wear an oven-mitt suit, but can't do his job and drives Jennifer and Mary Anne away until the curse is over.

Balki applies to the "Baby Quiz" TV game show for both couples. As it happens, Only Larry and Jennifer are accepted until a last minute drop out of the other contestants, in which Balki and Mary Anne take their places. The prize is a college scholarship for the baby.

Jennifer is two weeks overdue and has a few false alarms. Meanwhile, After Balki and Mary Anne went to the fair, Mary Anne goes into labor and has her baby in the driveway. Jennifer is told about a balloon ride Mary Anne went in and in hopes of going into labor, Larry and Balki take Jennifer up in the balloon.

Trapped on board a runaway hot air balloon, Larry and Balki must find a way to get back to Earth as Jennifer goes into labor.