The BoB (Bottles of Beer) series in the northern suburbs of Chicago, Illinois, comprises ninety-nine microcaches, named BoB 01 through BoB 99, a reference to the song "99 Bottles of Beer on the Wall". The caches were hidden by Genius Loci and Hutt using the common pseudonym Idiot Savant and are listed on Geocaching.com.
The caches are relatively concentrated, with every cache located within twelve miles of any other in the series. Many of the caches are within a half-mile of several others. Most of the caches are located near streets and other roads, making them very easy to access.
As a result, many geocaching teams tend to make "BoB runs", where they attempt to locate most or all of the caches in the series. Given the short distances between caches and the ease of access, this can be accomplished within a single day, usually ranging from five to eight hours for the whole tour. Many geocaching teams use stickers to sign the logs in order to minimise the time needed to visit a particular cache. This series is popular with geocachers as it allows their find score to be boosted by nearly a hundred caches.
- BoB 99 contains the "Legend of BoB"