Friend Owes Money but keeps putting it off?

It would be one thing if he were in hard times himself but he's obviously taken you for granted from this account of things. I would avoid doing anything for him. I would tell friends you share about this long standing debt and to warn them not to lend him money as he will not honor his debts. There is no way he should be paying that other guy back before you. That other guy buying a ticket should know how long you've been screwed over by this "friend" and that it will likely happen to him. He takes people for granted and deserves no sympathy or help.