Only temporary violations of Dude Space are allowed, i.e., Dude #1 is busy talking to a chick, so Dude #2 reaches over his leg to grab the Doritos.
On a couch that seats three people, properly alloted Dude Space would require both dudes to sit with the middle seat unoccupied.
Dude #2: "Sure, hand me a controller."
Dude #1: "Dude...what the hell are you doing?"
Dude #2: "Playing RS:V....why?"
Dude #1: "Scoot over...you're violating my dude space."