The BoB (Bottles of Beer) series in the northern suburbs of Chicago, Illinois, was a set of 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 were listed on Geocaching.com. All but the first and the last of these have been archived.
The caches were relatively concentrated, with every cache located within twelve miles of any other in the series. Many of the caches were within a half-mile of several others. Most of the caches were located near streets and other roads, making them very easy to access.
As a result, many geocaching teams tended to make "BoB runs", where they attempted to locate most or all of the caches in the series. Given the short distances between caches and the ease of access, this could have been accomplished within a single day, usually ranging from five to eight hours for the whole tour. Many geocaching teams used stickers to sign the logs in order to minimise the time needed to visit a particular cache. This series was popular with geocachers as it allows their find score to be boosted by nearly a hundred caches.
- BoB 99 contains the "Legend of BoB"