Try www.westernunion.com if the tourist is a friend and you don’t need the money order receipt thingy. If you have a credit card you can do it right now and the money will be there in what? minutes.
If the tourist has a bank account in the country you are currently in and you know the account number, you can just deposit the money into this account and let them take it out with their ATM card. This is by far the cheapest and easiest way.
Otherwise, you’re probably stuck doing a wire transfer if they need the money immediately.