don't know if its been posted:
Englishman, Irishman and Frenchman walking along a beach and fine a lamp with a genie, the genie says i'll give you 1 wish each!
the Irish man asks for lots of guiness the genie grants that 1
the Frenchman asks for a wall to be put around France so they dont get invaded again, the genie grants that one
the English man said tell me more about the wall the genie says its 150ft tall, with no exit
the Englishman goes
"fill it with water then please"