'Game of Thrones' Star Alfie Allen -- Whew! Thank God My Sister Didn't Play My Sister

Alfie Allen, best known as Theon Grayjoy on "Game of Thrones," came thiiis close to trying to bone his real life sister, singer Lily Allen -- but wait, wait ... don't freak out!

See, Lily almost played Alfie's sister on the show -- which would've been seriously awkward since he tries to grope his TV sis before he knows they're bro and sis. Yeah, GoT is confusing. And awesome.