If you initially choose not to have Kimmy read what her fiancé calls her Whence Thither book in the very beginning, it comes to bite her in the butt when she reaches a crucial fork in the road in West Virginia. She loses the Reverend after hitting a gas station run by Johnny Knoxville and, because she didn't read the book, she has no way of figuring out which way he went. He reaches the bunker before her and escapes with his second group of kidnapped women, taking them "to Florida, where everything's legal." If you chose to watch the baby left in the gas station, Titus's construction-worker husband, Mikey, appears to give you a second chance at it since you made the right decision.
Time rewinds to the gas station where Kimmy is given a choice between reading the book to the baby or letting Titus read. If you choose Kimmy, she'll read the book, which will later spark the idea she needs to figure out where the bunker is. If you choose Titus, he slings some hilarious baby disses, but Kimmy still doesn't figure out how to reach the bunker, so it's a pointless choice.