So stage door (where an actor comes out after a play to sign stuff) works like this: The actor can only sign stuff that is from the theatre, like programs or merchandise, posters etc. that was bought there. This is to make sure only people, that attended the play, have their stuff sign and you don't just have random fans from the street stand in line, taking the spaces of people that bought tickets. And so his signature doesn't just land on ebay or something like that. So if you're just standing there and give him whatever, he is not going to sign it.