Eric asks Matt to take his friend's daughter to the senior prom, but he is unaware of her tainted style and her being a harlot. Eric gets ""Snappy the Stegosaurus"" tickets from his ex-girlfriend for Ruthie. Meanwhile, Simon is uncomfortable after viewing a school film on the 'facts of life' while Ruthie learns the truth about her costume character hero. Also, Mary and Lucy trick their way into a date with boys they don't know, but the joke's on them.

In the third season-opener, Annie is feeling a little depressed since she's 3 months pregnant. Ruthie is pretending to feel a little pregnant herself. Lucy is following the dating advices from 'The Rules' book she has. Matt moves in an apartment with three attractive girls. Eric is looking for the perfect 20th anniversary plan for Annie. Mary gets a lot of attention from guys, which makes Lucy jealous. Although, one of Mary's 'guy' friends asks Lucy out. Matt finally comes back home because of girl problems he was having with his new roommates. Simon's girlfriend is acting a little weird. Eric and Annie tell the kids they're having TWINS!