Due to extreme stress cause by so much paperwork, Dave doesn't have time to go on vacation with the boys. In the morning, Simon shows his brothers a shrinking solution he created, which Dave drinks by accident. After Simon's antidote doesn't work and Alvin loses the house and recording contract at Dave's meeting, the boys decide they will go river rafting. Their shopping spree for the trip goes south when Dave runs off with the credit card, though is quickly caught. Once on the river, the boys crash their raft, losing Dave in the process. Fortunately for Dave, he wakes to find the whole thing was just a nightmare.
- "One Way or Another" originally performed by Blondie.
- "What'll I Do" originally performed by Irving Berlin.
- The title is a spoof of the 1957 film, The Incredible Shrinking Man, starring Grant Williams, and the 1981 film The Incredible Shrinking Woman, starring Lily Tomlin & Charles Grodin.
- Part of the Driving Dave Crazy DVD.