A reference to the way in which those who have taken alot of ketamine begin to walk. Ketamine in large quantities sometimes renders you suddenly incapable of doing otherwise simple things like climbing stairs. You sort of feel as if you are no longer sure where your legs start and finish, and you look as if you are trying to walk through dough.
'What the fuck is that guy over there doing?'
'I think he is just trying to get into his tent, but he has major ket-legs. Watch how he wobbles but never falls over!'