Enclaves are territory of one country inside another country. Most of such crazy entities are manifestations of Mr History's humour sense. The most complicated enclave system in the India-Bangladesh enclave system. This has the world's only counter-counter enclave. That is India has an enclave inside a Bangladesh enclave which is inside another Indian enclave :) This was a result of card or chess games between two Kings..And here we think that they dont have a sense of humour...But i dont think the residents of the enclaves share their enthusiasm in geography jokes and their life is a living hell with no facilities and having to negotiate international border for small things. The Dahagram-Angarkota is the only part-time enclave in the world , as the connecting Teen Bigha corridor is leased to Bangladesh during day time
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This is one topic where i found a site having much more detail than wiki
Update : These enclaves are no more, to the delight of the residents and despair of map enthusiasts, Indian PM Narendra Modi signed land transfer treaty with Bangladeshi counterpart Sheikh Hasina