Fill it up with water
Two guys, an Indian, a Pakistani are out walking together one day. These 2 guys come across a lantern. When they rub it, a Genie pops out of it.
'I will give you each one wish, that's two wishes total,' says the Genie.
The Pakistani said, 'I want a wall around Pakistan, so that no neighbors or infidels can come into our Paki land.' With a blink of the Genie's eye, 'POOF' there was a huge wall around Pakistan.
'Hmmmm', the Indian asks, 'I'm very curious. Please tell me more about this wall.' The Genie explains, 'Well, it's about 150 feet high, 50 feet thick and completely surrounds Pakistan. Nothing can get in or out.'
So the Indian says, 'Fill it up with water.'