Garlic is often kept in oil to produce flavored oil.

http://en.wikipedia.org/wiki/Garlic

Garlic is often kept in oil to produce flavored oil; however, the practice requires measures to be taken to prevent the garlic from spoiling. Untreated garlic kept in oil can support the growth of Clostridium botulinum which causes the deadly botulism illness; refrigeration will not assure the safety of garlic kept in oil.