And presumably the passenger's name is encoded in the barcode, which I guess is why the OP suggests printing the original ticket with the name of the friend tha

And presumably the passenger's name is encoded in the barcode, which I guess is why the OP suggests printing the original ticket with the name of the friend that bought it instead of just using the "forged" ticket at the gate. Though I'd also guess that the airline employees who scan the ticket at the gate almost never check that the name on the ticket matches the one displayed on their screen when they scan the barcode, so you'd probably be fine using the forged one.