I think the accepted explanation is that it's a plug socket for the aliens to recharge their space camel.
(
Carlossus,
Sat 19 Jul 2008, 14:00,
archived)
tasty space camel piesyou should try them :D
yum!
(yum!
discomeats This canoe,
Sat 19 Jul 2008, 14:01,
archived)