Any ideas if you can have a friend sign in with your gamertag on their machine and collect on this, specifically "Operation Completion"? I'd love to try and get that $50 off $100 coupon in time to jump on the $20 off a 3DS XL at Best Buy, but I don't think I'll be able to find a copy of Halo to borrow in time. Heck, even getting a friend to do it for me tomorrow would be pushing it to get the coupon by Saturday.
But would it theoretically work? Is that the sort of thing that would get my XBL account flagged?